How can I dismiss a frozen "Deleting Trash" dialog box?
Solution 1:
Try killall Finder in Terminal.app.
Solution 2:
Relaunch the Finder if you don't want to use the terminal. Apple menu > Force quit... > Finder > Relaunch.
Solution 3:
If you want to stop ONLY the Empty Trash process, open the Activity Monitor utility and force quit the Locum process.
Enter your admin password when requested.