A few projects have come my way because of company acquisitions and it’s always a pain for users to have multiple sets of credentials. The have a set for the company they used to work for, as well as the new company that acquired them. When using multiple sets of credentials in Chromium based browsers, I’ve found that when selecting the account to log into Azure DevOps with, doesn’t always work as expected.
To force a sign out from Visual Studio Subscriptions or Azure DevOps Services specifically, you can head over to https://aka.ms/vssignout in the same browser window that you’re experiencing the issues with.
That will force a sign out and should clear the currently logged in account on the back-end.