Apple - System Integrity Protection prevents Trash from being emptied

1. Shutdown your laptop.
2. Press Command + R and then the power button to boot into recovery mode.
3. Click the Utilities menu and select Terminal.
4. Type csrutil disable and press return.
5. Close the Terminal app and restart out of recovery mode.
6. Login to your machine normally and launch the Terminal app on your Mac by either searching for it in Spotlight or locating it in the Utilities folder under Applications.
7. In Terminal enter this command sudo rm -rf ~/.Trash/* it'll ask for your login password. That should clear your trash.

If that worked re-enable SIP.

1. Shutdown your laptop.
2. Press Command + R and then the power button to boot into recovery mode.
3. Click the Utilities menu and select Terminal.
4. Type csrutil enable and press return. Close the Terminal app and restart out of recovery mode.