Okay, enough sass. Get serious - you're a professional.
This issue requires a lot of focus and determination. Users approach our product expecting 100% uptime + functionality, and you're about to totally remove someone's ability to access the site. On top of that, it's also likely that the site owner isn't being entirely forthcoming with that person losing their access.
With all of that said, you just need one thing: the site owner's permission. Don't take another step without it!
Pretend you don't even have a fishing line, let alone a fishhook. Confirm with your friendly neighborhood accounts manager that this person not only has ownership, but authority. Once they're they're aware of the situation (along with them understanding the account is going to be completely deleted), and have authorized the process, then go ahead and remove them.
Or, you can also just tell the owner of the site how to delete admins so he/she can do it him/herself so you don't step on any toes.
In review:
- Find out who owns the site
- Speak directly with them for authorization
- Inform them that the changes will disable this user's account
- Delete the account
(Or Tell owner how to do it)
- Eat a snack. You earned it!