If, for whatever reason, you decide that you no longer need/want Sitebulb to have access to Google Sheets or Google Analytics/Search Console you can simply disable access through Sitebulb's global settings menu.
Navigate to Settings in the top menu, right next to Your Account
Find the Google Accounts tab
Find the relevant account (pay attention to the Type column)
Click Delete and confirm that you want to remove it from Sitebulb
Note that there are separate permissions for Google Sheets and Google Analytics/Search Console.
You can remove one permission and leave the other intact, just be sure to select the right one when you come to do this.