A mailbox archive in Enterprise Vault will typically have on it, something called 'inherited permissions'. This is the owner. From time to time it might be necessary to remove this access, for example if someone is transferring to a different department or region.
The permissions show up like this:
If you try to remove them using the Vault Admin Console, you get the following pop-up:
What you have to do is use EVPM and Zap the Archive. How to do this is described in this technote: http://www.symantec.com/business/support/index?page=content&id=TECH44818. Once that's done, refresh the list of archives in the VAC, and the permissions will be gone: