I recently downloaded "Install macOS Catalina", "Install macOS High Sierra" and "Install macOS Mojave" and then wanted to delete them again, so I moved them to the trash, but trying to empty the trash gives the error that they are apparently being used. Even after a system restart it still happens. Trying to delete them from the Terminal via sudo rm -rf gives the error "the directory is not empty". How can I get rid of these files?
I think it's extremely sad that nobody at Apple wants to help me out here. Is it intended that we download official installers that cannot be deleted anymore?
Unfortunately the installers are protected by the System Integrity Protection (SIP ) system. To delete the installers boot your Mac into Recovery mode (CMD-R) and open the terminal application from the menubar and execute the following command to disable SIP.
csrutil disable
Restart your Mac. You should be able to delete the installers. After you delete the installers boot back into Recovery mode (CMD-R), open the terminal application again and execute the following command to re-enable SIP.
csrutil enable
Restart your Mac and enjoy.