Yes - in QuickUpdate you can do all the operations eg. add/remove customers in groups - in the first screenshot, instead of adding groups by clicking "+", you can select groups from the right side and click delete ("trash" icon) and those groups will be removed from the respective customers (or vice-versa depending how you see it).
Btw you are struggling to solve your issue with queries because of the falsely promoted idea that "you can solve it with a query" - the whole point of having modules is to facilitate a specific functionality that can be performed repeatedly.