Expand your search menu by clicking the down arrow. There you will be able to choose all files or specific ones, all owned by you or owned by anyone.
Now enter the name of the person you want to delete access for > Search
Changing to the list view, if you haven’t done so yet, might make life a little easier. You can find that on the top right close to your settings. Once the list appears, scroll down, keep scrolling, and more scrolling until the list stops expanding and all files are shown on your screen.
A few keyboard shortcuts will come in handy.
CTRL+A = select all
Click first – Hold shift – click last = all in between are selected
Click first – hold CTRL – click next – click next = all clicked will be selected
Right click and the select the menu item “Share”
Now you should see this (I selected all):
Now you can remove access for any user with the documents that you own by clicking the little grey x or change level of access.