Instead of delete or suspending the acid, you may want to consider just changing the password. You don't know if this acid is being used for automated jobs, scheduled jobs or automated transactions. Deleting the acid will cause them to fail. Changing the password will prevent the user from using their id.
Add the TRACE attributes to the acid so you can monitor its usage via TSS ADD(xxxx) TRACE to determine if it is being used by any scheduled, automated jobs, transactions.
Run a TSSUTIL REPORT(ACID) to determine where it is being used and take appropriate action.
When you are comfortable after a certain period of time, suspend the acid. Then, after a certain period of time without problem, proceed to delete the acid, if you wish.