Q:

How to deal with subordinate know-it-all's

Imagine your boss or another department manager asks you something. You start formulating the idea in your head... and before you can speak Mr. Know-It-All barges into the conversation and tries to help and answer.
Now you are promoted to be the boss and manage your team including Mr. Know-It-All
You need some help from your team. Or you want to inspire some teamwork and brainstorm ideas from everyone. Mr. Know-It-All is more than ready to help - as long as he moderates the show, or is the only one who speaks.
Moreover, it seems like everyone is used to his proactive interventions and thus all are reluctant to speak out first because Mr. Know-It-All always has to say something anyway. Or, whatever is said needs to be approved or criticised by Mr. Know-It-All. He has the final word.
As a new manager, I am confused about how I should behave with a person like this.
Personally, I feel a bit irritated that he tries to take matters into his own hands - it feels as if he undermines my and others' ability to follow the procedure I started.
Over time I have grown so reluctant to speak to the team as a whole that I prefer talking to everyone individually - because that seems the only way for me to communicate freely with everyone, without this guy barging in.
I am not sure whether my behavior is correct, nor whether I should be too concerned about him. Am I wrong to be irritated? Should I give him more of the limelight and try to recognize his insights as valuable so he can be groomed as my "successor"?
Or should I privately tell him something like "You know a lot and that's good. You just need to give others a chance to speak and come up with their own ideas. Also if you have any criticism, tell the person in private rather than in front of everyone!"
How can I deal constructively with this type of person?

A:

You were the one promoted to manager, so even if he thinks he knows all, others don't appear to agree.  However, you can't let him take control, and refusing to control the situation while in a group is letting him have the control.  So, you'll need to start dealing with it (thus, your question).
Here's some advice from Alison Green on dealing with annoying co-workers:

The-Know- it-All
Everyone can benefit from a knowledgeable co-worker, but the one that seems to have done it all or knows everything about anything can be downright annoying.  While it may be satisfying to tell that co-worker to shove it, that could land you in hot water with your employer.
How to handle it: Instead of getting angry, Alison Green, writer of the Ask A Manager Blog, advises to just ignore the know-it-all.  “The more you can ignore this person and not let them get to you, the better,” says Green. When the co-worker offers unsolicited advice, Green said to thank the offender and say you’ll consider it. “If you find yourself getting frustrated, comfort yourself with the knowledge that this person is widely considered obnoxious; you're definitely not the only one annoyed.”

To add to that, since you're now the manager, go ahead and thank them, and then ask if others have input.  In other words, listen and then get others to speak too.  If he interrupts them,  interrupt him back and say "excuse me, I also wanted to hear what Bob says."
If the interruptions continue, then speak to him privately, and say something like "you interrupt when others are speaking, and that doesn't allow us to work as a team.  I would like you both provide input but also to listen to others, and quit interrupting.  Can you do that?"  And wait for his answer -- it needs to be yes.  (If it's no, then a PIP may be in order.  Seriously.)  You may have to do this a couple of times, especially as it is probably a habit for him.  But you need to be clear that others do also speak, and he is to listen and not interrupt when others speak.  You may need to privately encourage the others to speak up as well.
It will be a process, but you can only effectively deal with it if you really do deal with it.  Avoiding it isn't helping.

A:

You have to let go of your frustration.  You're the manager, and it's your job to deal with this situation.  It's especially your job to deal with this situation if members of your team have complained about his behavior, either formally (such as in a peer review during your annual review process) or informally.  
You say that he's a know-it-all, but I don't see here whether he actually is as smart as he thinks he is.  If he is smart, then your challenge is to improve his interpersonal skills so that he's not constantly stepping on others' toes.  If he isn't quite as smart as he thinks he is, then you both have to improve his interpersonal skills as well as improve his job skills.
You need to have a conversation with him about the issues that you have observed.  It's probably not worthwhile to dump everything on him.  You can either pick the top issue that you see, or you can take advantage of a particular situation when his behavior is getting in the way of the team dynamic or team goal.  In either case, you should discuss his behavior with him during your next 1:1 meeting with him.  (I presume that you're having regular 1:1 meetings with everyone who reports to you.  If not, this might be a separate issue that you address, so that you know what's happening with your team and so that you can provide timely and actionable feedback to him.)  Whichever issue you choose, you should have specific examples of his behavior and how it impacts you or the team, and you should have specific and actionable feedback about how to improve.  Then, in subsequent 1:1 conversations, you need to discuss how he's doing.  Changes in such behavior take time, so this will be an ongoing conversation.  As improvements to the first issue are made, you can begin to address other behavior issues that he is displaying.
You should also talk to your manager about the situation.  Part of your manager's job is to help you be the best manager that you can be.  You can discuss the problem with your manager and the steps that you are taking to address it.  Your manager might give you additional ideas about how to address it, especially if this person has been on your manager's team for some time.  
Avoiding the situation is not doing anyone any favors.  It's not helping your team, it's not helping Mr Know-It-All, and it's not helping you be successful as a manager.  Uncomfortable situations are part and parcel of your new role.  

A:

First, you have to decide how much of the know-it-all's expertise you need compared to everyone else's. Then you'll know how much risk you can take to push this person into some more socially acceptable behaviors.
Privately let this person know there is a problem and without a willingness to make some changes, he's going to suffer some consequences. He is going to have limited involvement in projects, planning, decisions, etc. 
Don't expect the change to happen right away. Start with small steps. Suggest he start letting others answer first without providing any negative feedback (at least not right away.). Encourage listening for other ideas he agrees with.
The rest of your team needs to learn to stand up for themselves if they want their ideas heard. They can't just hide behind the "know-it-all" as an excuse. The goal is to provide good solutions to problems. That's their job. In a team environment, you have to be willing to standup and defend your ideas if they don't match everyone else's. As the manager, you need to make sure that everyone understands that the best ideas aren't the ones shouted the loudest, but those kept in silence, have no chance at all of being heard.

