Can't completely empty Trash!

I can't completely empty the trash, even after restarting.

Another issue that is related to the Trash: I want to copy some files to a USB pen drive. When I click the "Get Info" to check the availabe space on this pen drave, I am told by the system that there are more than 6 GIGA Bytes available. But when I try to copy 5 G Bytes into that pen drive, the system says there's not enough disk space!

OK, I was told that the trash is also kept on the pen drive. I erased (formatted) the pen drive, and still, same problem.

So, please let me know how to

- completely erase the Trash

- Make available the disk space that is supposedly on the pen drive.

I am attaching a png file with the folders that WILL NOT get erased from the trash. I think they are backup files from Lightroom

Thank you