Delete old archive accounts?

[fnbwaseca]

To free up some space I would like to delete old archive accounts off our system. I created new archive accounts using zmarchiveconfig enable user@domain.com. Then I did a full system backup and moved that to an offsite archive tape. I also have backups on a NAS storage if I need to access the accounts.

I checked and mail is going into the new archive accounts so now I would like to delete the old ones. However, when I go to delete the archive accounts I get the following error "Warning! One or more of the selected accounts are special system resources. Deleting these accounts may cause unexpected errors."

Is it safe to delete these old accounts or will it actually cause problems?