Disable user

I was able to find an issue about this but honestly the solution wasn't clear at all.

We have a couple of employees who have left the company and naturally we want to remove their access.

Is it possible to remove or disable their accounts but preserve anything they have worked on? I mean their commits, and also if they were repository creators we obviously don't want to lose those repositories.

Can someone (preferably from Gitlab) give some guidance on this?

Thanks a lot!