Having problems with a file that will not delete from the Trash?

Simply hold down the "Option" button when you select empty trash.

it should trash the file, if not unlock the file if it's locked.

All you do is remove the file, -> Get Info -> UnLock -> Then trash it.

Same goes with ejecting a stubborn file,
Make sure all programs within the file are closed,
for instance, Simple text or Acrobat Reader, if they are opened inside a
locked image file and still running on the comp, this will prevent you from ejecting
a stubborn image file.

best to all