That wouldn't work here and in most of EU.The rule is to remove credentials at least 2-3 days before his last. He can use his final days training his successors.
Employment laws (quite rightfully if I may add) do not allow you to remove their access to anything until their last day of employment. That's when they turn over their phone, laptop, keys, access cards, etc and that's when their accounts are terminated. I know because I worked as an IT admin and worked with HR people on account termination for those employees who were either let go or quit.
And if you are asking yourself why, it's because in normal countries people are presumed innocent until proven guilty.
TL;DR -- you can't treat your employees like criminals (or rather you can, but then don't act surprised when they do eventually fulflill your expectations).
On a side note here it is customary that people who are leaving use their vacation days right before they leave so they usually don't even come into office until the last day. It's also customary to make a farewell party with some food and drinks unless a person was really bad and relations are tense.