What can you do to secure the google drive?

One of the options I’ve searched for is – who have I shared my files with ?

In the search panel of the drive G Suite you can set to: parameter and set some email or regex there to get all the shared items with that person. Overview and remove from where it is needed to remove.

Is there a better way to remove the permission from all the files together that just go through one by one at the G Suite basic?

There is a way to upgrade the G Suite to premium and then you have Drive permission tool, but it’s too rich for my blood right now.