How to remove auto-mapping in Exchange 2010

I took the following steps on our Domain Controller server to remove the auto-mapping feature.
1. Open the tool ‘ADSI Edit’ from the Administrative Tools.
2. Browse to the offending user(mailbox) that you would no longer like to be automatically mapped to particular users.
3. Right-click the account and select Properties.
4. In the Attribute Editor, select ‘Filter’ in the bottom right corner.
5. Ensure ‘Show only attributes that have values’ is ticked.

6. Browse in the list attributes and select ‘msExchDelegateListLink’. These are the list of users that the account will automatically map to (populated by those with Full Access to the mailbox).

7. 7. Select Edit, click on the user you would like to no longer auto-map to and select Remove.

8. 8. Press Ok then Apply.