You can disable MailScanner temporarily by clicking the "MailScanner
Disable" button in the WHM MailScanner Front-End (in the MailScanner
To re-enable it, simply click the "MailScanner Enable" button in the WHM MailScanner Front-End.
If there are emails waiting in the MailScanner pending queue, the waiting emails will not
be processed by exim until MailScanner is re-enabled.
To permanently remove MailScanner from your server, see this FAQ: How can I remove the MailScanner Service package from my server?