Hello there, I'm Gopal an Independent Advisor. I will try my best to help you.
I understand how frustrating it must be to be stuck with a malfunctioning GOG Galaxy app and unable to play your games.
Please try to end the process in the background and then uninstall it.
Press Ctrl + Shift + Esc to open the Task Manager. Look for any GOG Galaxy-related processes in the "Processes" or "Details" tab, such as "GalaxyClient.exe" or "GalaxyCommunication.exe". Right-click on each process and select "End Task" to terminate them. This should ensure that the app is not running in the background.
Then, you can follow the below steps to uninstall it
Open the Settings app by pressing Windows + I.
Go to "Apps" and click on the "Installed apps" option.
Find and select the GOG Galaxy app from the list.
Click the three-dot button and choose the "Uninstall" option.
I hope this will help you to sort out the issue. Please let me know if you need further assistance. Thank you!
Regards
Gopal