Q:

How to switch from a Slack team account to another

A collaborator recently invited me to a Slack workspace I was already subscribed to, which I thought was weird but I accepted.
I just found that my original account was using my xxx@gmail.com address and he invited me with my xxx@company.com address.
I am now logged with the company email address and I don't find how to:

completely log out
switch to another account based on the email address

I guess Slack is not made to use with multiple team accounts for 1 user but I feel locked in this accidental situation.

A:

Finally found how to switch account:

In the workspace, click on the workspace name (top-left corner)
At the bottom of the menu, click "Log out from: workspace"
Confirm on the web page that opened. Then click "Log in back"
Enter the email & password to log in with the other account.

I use Slack in another language, I translated the menu items as I read them.

