When you give Refer.com permission to access your Google account, Refer.com is saved as one of your "Connected apps and sites" in your Google account. Google allows you to connect your account to a limited amount of 3rd party applications.
If for some reason you need to reset your Gmail connection in Refer.com or want to delete a gmail address from your connected accounts in your Account Manager, you will need to go into your Google account and remove Refer.com as one of your connected apps.
Follow these steps to disconnect Refer.com from your Google account:
First, log in to your Gmail account and click on the "Google apps" icon in the upper right and then click "My Account."
Next click on "connected apps & sites"
Here you will see all of the different apps you have connected to your Gmail account*. You will need to find "Refer.com" and click on it. Then click the blue "Remove" button to disconnect Refer.com (see screenshot).
From here you will want to go back in the Manage Accounts page on your Refer.com software and go to "Connected Accounts" and delete your existing synced Gmail account.
Finally just click "Connect" and reenter your Gmail address and Gmail password and you are good to go