Disassociate an Apple ID from a computer There's a work computer (iMac) I'll soon stop using, which might be used by other people in the future.

While I've mainly used a separate work-only Apple ID on the computer, I suspect I may have used my personal Apple ID on the computer from time to time.

I want to make sure that my personal Apple ID isn't used in the future on the work computer. How do I ensure this is the case?
Go to System Preferences, and check "iCloud" and "Internet Accounts". Sign out where necessary, and once neither of them list your personal account, you're good to go.

You may also want to make sure your web browsers don't remember any of your passwords.