14.5.3.1 To Enable a User with Delegated Administrator Console

You can not disable a user from the Console. You can remove calendar service and then re-add them. To re-add the service, select the user from the User List page and use the Assign Service Package wizard to add the calendar service package to the user's LDAP entry. The user is automatically enabled.

This is the same procedure used to add calendar service (14.5.4 Adding Calendar Service to a User).