Did you try restarting first and then emptying the trash bin? If that doesn't work, use a force (hold option key while selecting empty).I have a PDF file in my trash and when i try to delete it I get a message that says the file is in use. I obviously have the file closed and in my trash, so how can it be in use? Any advice? Thanks!
The terminal command worked. Do you know why this happens in OSX? I never had this problem back when I used windows computers.You may find some useful ideas here:
You can't empty the Trash or move a file to the Trash
Solving Trash Problems
Can't move files to trash
Can't Empty Trash on a Mac