If your website is hosted with us and you want to use a third party email provider such as Gmail you will need to change the MX records for your domain.
Under the DOMAINS section in cPanel select the icon called "Zone Editor".
You will then be presented with a list of domains you are able to add, amend or delete DNS records.
If you click "Manage" you will then be shown a current list of DNS Records for the domain that you are able to alter.
If you select "Edit" you can then set the destination for your MX record as required.