Thanks to decox123’s contribution, now I know how to solve the “VoiceTrigger is in use” error occurring when I was trying to empty the Trash on my Mac.

I was having the same issue and followed your recommendation and it worked for me too. Here are the exact steps I performed:

Disable System Integrity Protection
Click the  menu.
Select Restart…
Hold down Command-R to boot into the Recovery System.
Click the Utilities menu and select Terminal.
Type csrutil disable and press return.
Close the Terminal app.
Click the  menu and select Restart….

Login normally, then Empty the Trash Can

Re-Enable System Integrity Protection
Click the  menu.
Select Restart…
Hold down Command-R to boot into the Recovery System.
Click the Utilities menu and select Terminal.
Type csrutil enable and press return.
Close the Terminal app.
Click the  menu and select Restart….

All done….