Please be aware this is for VPS and Dedicated Server clients only.
1. Log into your WHM through your Core account.
2. In the top left corner, type in "mail-server" in the search field.
3. Click on "Mailserver Configuration"
4. Under "Protocols Enabled", uncheck POP3, scroll to the bottom of the page, and Save Changes.
You have now successfully removed POP3 mail service on your server.