Admin access
In a previous job in the early 2000's, where I was IT Manager (and I was also 50% of the IT team), I was made redundant, partly enabled by underhand reassigning of roles. We had an internal meeting where the organisation chart was displayed. I pointed out that they had me down in the wrong role, but it was brushed over - I should have seen the signs...
Anyway, on the day they called me down to tell me I was redundant, they asked someone else to revoke my admin rights and changed the admin password. I was allowed to go back to my desk for the rest of the day to copy off my personal files from my computer. As I had been logged in the whole time, I still had full admin rights and could have done anything, but obviously didn't do any damage. I did copy off a few customer directories from a server so that I could make direct contact with them after the event and actually did some work for many of them.
A few months later, after the redundancy period was up, I received a call asking for the password for a specific system. I told them what my rates were for consultancy and they never bothered me again. They lost many knowledgeable developers due to the way those of us who were made redundant were treated and eventually went bust.