T56A SFB Force Logout from Lock Screen

[keaya]

When the phone is registered to Skype for Business Online.
By default the user will enter a 6 digit pin etc.
After the timeout the lock screen is displayed.

Is there a way for another user to forcefully log the user out from the lock screen? (So they can use it. Assumption is they do not know the other users lock code etc)
Pressing and holding down the redial button does not give the "Reset to factory setting option" etc

Thanks for any advice