Google Drive Revoke Shares to All Documents for User

1. From the list of folders on the left, find an item that says "All Items"
2. Check all items
3. More -> Share
4. You will see the list of all users that you have shared documents with, just delete the user from the list

Reference: http://www.findyoursocialmediazen.com/remove-user-on-all-google-docs/