To get changes made to your DNS settings as far as your MX record, A record, C NAME, you will need login into your cPanel
Note: If you are using Windows Hosting then see from bottom (last two steps)
From here you can delete old MX entry or Create New MX entry as per your requirement.
To Change Your A or CNAME record click on DNS Zone Editor
You can update or Delete any Record as per your convenience.
you can submit ticket from your client area, if you are getting any issue.
For Windows Hosting:
If You are using Plesk Panel instead of cPanel i.e. your account is in Windows Server Then click on DNS settings from your plesk panel
Now Delete. Create or Edit DNS records as per your requirement from following Window
For more information read complete knowledgebase
