My iMac has too many icons open and I can’t close any. I restarted with a safe start but still can’t close

+1, please use Force Quit to quit apps. To Force Quit, click the Apple symbol in the upper left of the display and open Force Quit, then select the app(s) you want to quit and then will close.

After you have done this, please do the following to see what is installed and what may be causing this problem.

Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click https://discussions.apple.com/docs/DOC-250000211

I’m not sure what you mean, do you mean too many apps open in which case you can do a force quit.

https://support.apple.com/en-us/HT201276

You don't exactly close an icon, you quit an app. Once you quit the app, it's icon stays where you put it. Do you want to move the icon (Alias) off the desktop or quit its program?