There are two ways to revoke’s access to your Google Drive account: 

To revoke access but keep your existing libraries:

Navigate to your Google Account Settings, select Security, followed by 'Manage third-party access' under the section ‘Third-party apps with account access’.  You can then select, and click ‘Remove Access’. 

To revoke access to and delete your libraries:

Open your Google Drive, select the settings cog and click on Settings. Press ‘Manage Apps’, then locate You can then expand the options menu next to, and press ‘Disconnect from Drive’.