You changed your mail service but you still have Google App Records?
Start by going to your Manage Domains Page :
Find your domain:
Then click the Edit under “Fully Hosted/User“
On the next page you will see the site options, and you will See “Additional Google Apps” , uncheck that and save your settings:
After saving the setting the domain will need to update. After the domain has updated then the dns will be removed from that domain. Then they will need to propagate away. Please note dns changes can take 4-48 hours to fully propagate across the internet.