Site Properties:
1. Launch the Enterprise Vault Administration Console, expand the Directory container.  The container immediately below the Directory is the Site container. Right-click the Site name and select Properties.

2. On the Archive Settings tab ensure the option Users can delete items from their archives is checked.
 

Retention Category:
 

3. Launch the Enterprise Vault Administration Console, expand the Directory container. Expand 'Site'. Expand Policies. Expand 'Retention and Classification' and select Categories.
4. Right-click each retention category and select properties.
5. On the Details tab verify that the option Prevent user deletion of items in this category is not checked.
6. When performing deletions in only the Journal Archives, restart the IIS Admin Service and attempt to delete the items
7. When performing deletions in Mailbox Archives, synchronize the mailboxes from the appropriate Mailbox Archiving task, restart the IIS Admin Service, and try deleting the items
 

Note: It may be necessary to clear the Internet Explorer cache and restart Internet Explorer before successfully deleting the archived items.
 

The error below is returned during an attempt to delete archived items in Enterprise Vault for Microsoft Exchange and IBM/Lotus Domino