Co-author contributed almost nothing and is blocking publication Alice and Bob have co-authored a paper together. The contribution (data collection, analysis, writing) was 100% Alice and 0% Bob, except that the original idea was initiated during a conversation between Alice and Bob. Bob acknowledged several times in private that he did not contribute to the project, but he claimed co-authorship for the idea and Alice did not object to that. Alice spent almost an entire year working on the project. Bob spent less than a couple of hours in total. A manuscript with both names has already been circulated, submitted and rejected from one journal.

Bob is now trying to block the publication of the paper due to a personal conflict with Alice. In the meantime, Bob became envious of Alice's early successes and decided to do everything to slow down her career, even at the expense of his own publication record. Bob is already tenured and has no pressure to publish. Alice, by contrast, needs more publications for her forthcoming tenure review. Of course, Bob never explicitly refused to submit the paper. But instead of sending it to a prestigious outlet (where the paper would have a good shot) he insists that they send the manuscript to a non peer-reviewed and unknown journal, which would not help Alice's tenure case. Of course he makes no effort in trying to find an agreement, as he would be happy not to submit the paper at all. Clearly, his decisions are driven by spite and malevolence only and he takes great care into not writing anything incriminating for him.

Is there anything that Alice can do in that situation? Does she have to resign herself to never publishing the paper? What are the risks for her if she removes Bob's name without his agreement and submits the manuscript on her own?

PS: as a response to Captain Emacs' comment, Bob's only contribution was to say "why don't we study the causal effect of X on Y?" in an informal conversation. Alice did absolutely all the rest (literature review, design of the protocol, data collection, analysis, conference presentations, etc.). But there is no evidence of this, other than the fact that Bob would be unable to answer any question that goes into the detail of the paper.
As with the another answer, I couldn't help but notice the almost literary way in which the Bob character is depicted:


  Clearly, his decisions are driven by spite and malevolence only


Unless the OP is Bob (what a twist!), she is really not in a position to make that claim.  In my experience, in 99% of all human behavior, after sufficient scrutiny, one finds that "driven by spite and malevolence only" is not the right explanation.  Moreover, I'm not sure I've ever seen an academic make a professional decision to spite someone else even though it hurt their own career as well. Regarding this the OP wrote:


  Bob is already tenured and has no pressure to publish. 


Now I really think the OP cannot be Bob, because tenured people still have pressure to publish.  The stakes may be different from that of their long term academic survival, but they are not necessarily lesser or viewed as lesser by the tenured faculty.  

Anyway, here's the heart of the matter in my mind:


  The contribution (data collection, analysis, writing) was 100% Alice and 0% Bob, except that the original idea was initiated during a conversation between Alice and Bob. Bob acknowledged several times in private that he did not contribute to the project, but he claimed co-authorship for the idea and Alice did not object to that.


I accept the premise of the story that Bob has done nothing on the paper past one initial conversation and is now (for some reason or reasons) acting against its timely publication in an appropriate venue.  Which is terrible behavior on his part, of course.  However, I must point out that Alice has also made a terrible mistake at some point in the process.  Bob "claimed" coauthorship for a project that someone else worked on for a year and that he had one conversation about.  That's egregiously improper behavior.  You shouldn't "claim coauthorship" under any circumstances; you should propose coauthorship and that proposal should be accompanied by specific proposed contributions.  If Alice went away after one conversation and worked for an entire year without telling Bob what she was doing, that's a mistake (and by the way, it could much more plausibly be part of what made Bob upset).  If she did tell Bob what she was working on, she should have clarified that if he wanted to be involved in the project he needed to do....something.  And no matter how they get to the endpoint, where Alice has a paper and Bob asks her to put his name on the paper, she needed to object to this.  In fact (although this is not the point), Alice's lack of objection could be construed as academic dishonesty: it misleads the reader as to the level of Bob's contribution.  

This act of misleading seems to have come back to bite Alice in the behind.  It is much more awkward for her to take back sole control of her work after having submitted the jointly authored paper.  However, it may still be the right thing to do if the publication of the paper is important enough to her.  I do not see an ethical problem with Alice deciding to pull away with her work, given that it actually is solely her work.  That she may not be able to prove that to the satisfaction of all interested parties makes the action more risky, not less ethical.  If Alice and Bob really cannot agree on where to submit the paper, Alice has the right to say "I'm sorry it didn't work out.  I am taking my work with me...which as you know is everything except the original idea, which I will credit you for so that you can write a paper on your alternate development/implementation of the idea if you choose."  She should not allow the hypothetical threat of Bob's academic dishonesty (i.e., the possibility that he might tell other people that he did the work) to hold sway. 

In fact, if Alice convinces Bob that she is serious about pulling away, then with any luck he will see that he has nothing to gain by pressing a fraudulent claim that the work was his that he wouldn't gain better and more easily just by allowing a joint submission to the journal Alice wants.