You can uninstall the Betternet Mac App the same way that you uninstall any other application from your machine. Go to Applications, find the Betternet folder and move it to trash. However, you need to make sure the Application is closed.
1. Open your "Finder"
2. Click on "Applications" on the left side.
3. Locate "Betternet VPN"
4. Right Click on "Betternet VPN"
5. Select "Move to Trash"
You are done!