Deleting files from iMovie on Mac with 10.15.7

I've read previous posts here that say to delete a project file from iMovie you delete them from All Events under Libraries. Problem is, I can find no way to delete the files in All Events.

I first deleted them from the Projects page then came to All Events in Libraries and all the files are there by title listed at left and by thumbnails at right.

There is no "Delete" shown anywhere and clicking on the delete key on my key board doesn't do it so what am I missing, why can't I delete them from All Events?

What's the secret to clearing out my iMovie files?

Thanks.