Downloaded Catalina installer on Big Sur, now can't trash

I downloaded the Catalina Installer on my Big Sur machine to resurrect another Mac.

Now that 8gb file is stuck in my trash can. The error message is:

I've tried:

• Option then trash
• Rebooting
• rm ./Trash via terminal as admin and as another user (operation not permitted)
• Third Party trash application
• Changed file permissions
• Restored the image to its original location then opened it and tried to delete packages manually.

Any more ideas that I'm missing? I'm assuming that Software Update feels like the file is still needed, or hooked into it some how but I can not figure out where.