My first task at my last job was removing access to an employee being let go. I had just gone through onboarding so I knew every (documented) service we needed to handle. We live tested it on my own accounts, measured the time before I noticed, and then proceeded to successfully go through the checklist.

Except not everything was properly documented, and it turned out the employee had given admin rights on some resources to a contractor which proceeded to wreak havoc on their behalf (the 'rm -rf' kind). Eh!