How to change my MX record?
The MX records for your domain are set from:
cPanel -> MX Entry
At the MX Entry menu choose the domain for which you wish to change the MX records. At the displayed page delete the MX records which you no longer need (presumably when you change MX records you will no longer need the old ones). You can do that by clicking on the Delete button at the corresponding MX record.
Next you have to create new MX records. You can do this from the Add New Record field. Set the priority(the lower the number the highest the priority is), fill the Destination field and click on the Add New Record field to create a new record. The Priority field determines which one of the domains(destinations) will serve the incoming email messages. If this domain is not accepting the email message it will be served by the domain with the next highest priority and so on.