FCPX not deleting render files?

I have a Library that I have moved all events and media out of in preparation for deletion

However, it's still 110GB in size

Obviously, I wanted to make sure that all the original content has been moved, so I opened the package contents

and saw a bunch of large files under the "render files" folders (and no original media 👍)

But when I select the library and go to "Delete Generated Library Files" and select all the options, these files still remain in place...

Shouldn't these files be deleted??

Thanks in advance for your help 🙏