Systematic Transition of Keys from Ex-Employees to New Users

How to transition keys from an old user to a new one? We've had many keys created by ex-employees, some whose email accounts are deactivated. We want to centralise it to another email ID / account within the Clay workspace. When we try adding the same key, it gives an error. I can try deleting them and adding them afresh, but isn't there a systematic way of transitioning the keys without breaking operations?