The Ai answer reply is incorrect.
If your Windows 11 version is fully up to date, you should have the 'End Task' option on the right click menu of open app icons on your Taskbar.
If that, option is not available, open the Settings App.
Go to System - Advanced, do you have the setting and if so, is it enabled?
If you do not have that setting available, your Windows 11 version may need to be updated.
Click your Start Button, type winver and hit Enter
Please provide a screenshot of the resulting dialog.