Cannot delete an old Mac OS X Update Installation .app - it won't go away!

I have an old install mac OS.app downloaded via the App Store on my OS X and it is very unusual. I deleted it manually, but cannot EMPTY the Recycle Bin.
Any attempt to empty the bin fails because it says that the file is in use (which it isn't).
I've tried EVERYTHING; right-clicking it and clicking Delete Forever and I get this:
[https://discussions.apple.com/content/attachment/0614a7fb-ce2c-4c9a-9915-4891fe6c4338]

Naturally, next I tried doing what the dialog suggested, making sure that the permissions were all ok. Still, NADA.
[https://discussions.apple.com/content/attachment/f802348b-4320-40e1-ac65-847a4b9a87b9]

I've tried rebooting into SAFE MODE, no luck. I've tried renaming it, even trying to use third party tools to wipe it. I can't seem to clear this file, and it is eating up 7.74GB of space on my brand new iMac.

HELP somebody!!

UPDATE: see screenshots here: https://discussions.apple.com/thread/251772387
The lower-level commands will probably provide more information:
  1. Open Terminal

  2. Type cd /tmp and press Return

  3. Type sudo rm -r (note trailing space)

  4. Drag the installer app to the Terminal window

  5. Press Return

  6. Type in your administrator password

  7. Press Return

Depending on the result, it may remove some of the contents, or none at all, but you should get a specific error message.
A command like rm -r is very dangerous which is why I recommend changing the directory first.

I have tried using terminal to delete two old installer dmg files with no luck! Any suggestions? Here is the terminal content:

The default interactive shell is now zsh. To update your account to use zsh, please run chsh -s /bin/zsh. For more details, please visit https://support.apple.com/kb/HT208050. iMac:~ allyson$ sudo rm -rf /Users/allyson/.Trash/Install\ macOS\ Mojave.app  Password: rm: /Users/allyson/.Trash/Install macOS Mojave.app/Contents/SharedSupport/InstallESD.dmg: Operation not permitted rm: /Users/allyson/.Trash/Install macOS Mojave.app/Contents/SharedSupport: Directory not empty rm: /Users/allyson/.Trash/Install macOS Mojave.app/Contents: Directory not empty rm: /Users/allyson/.Trash/Install macOS Mojave.app: Directory not empty iMac:~ allyson$ 

Cannot delete an old Mac OS X Update Installation .app - it won't go away!
 
 
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