How do I Remove Google Permissions?

To revoke a script's access to your data, follow these steps:

    Visit the permissions page for your Google account.
    Click the name of the script whose authorization you want to revoke, then click Remove on the right, then OK in the resulting dialog.

How do I Block Access To my Google Account?

Block a device

1. Sign in to your Google Admin console. Sign in using your administrator account (does not end in @gmail.com).
2. From the Admin console Home page, go to Devices. 
3. Choose an option:
4. Locate the device in the list and click its name.
5. Click Block.

How do I turn off third party access in Gmail?

Remove site or app access

1. Go to your Google Account.
2. On the left navigation panel, select Security.
3. On the Third-party apps with account access panel, select Manage third-party access.
4. Select the site or app you want to remove.
5. Select Remove Access