To remove our mobile add-on you would need to do as follows:
1) Log into Gmail and go to your Gmail settings.
2) Click on the Add-ons tab and check to see if Mailtrack is listed, then click "Manage".
3) A G Suite Marketplace window should open, and from there you can remove the Mailtrack for Android add-on.
5) Close then re-open the Gmail app on your phone to complete the uninstall.