Hello
Running 32 bits application in v3.07.
When I click on the uninstaller, it tells me “Please close Mp3tag before and press OK”.
There is no opened app nor active Mp3tag process in the task manager.
What can I do to uninstall it ?
Can you check if any window you have open has "Mp3tag" and if so, close it?
Thank you for your quick answer 
I closed everything and rebooted the PC but didn't help.
I finally resolved this issue by uninstalling from the Windows configuration panel and not from the uninstaller executable found in the directory.