If you need to remove RMail from Gmail, please follow the following steps:

Remove RMail for Gmail Extension

1. On your computer, open Chrome.
2. At the top right, click the 3 menu dots next to your profile icon
3. Click the option More Tools in the resulting drop down menu
4. Click the Extensions option from the resulting drop-down menu
5. Locate the RMail for Gmail extension pane and either disable the toggle button or remove the extension.