When you delete files in Google Drive they go to the “Trash.” The files stay in the trash until you delete them. Click on the “Trash” category on the left hand side in Google Drive. If you are like me there are thousands of files in there that you had deleted.
Deleting the files one by one is too tedious. Use Control A to select all of the visible files. (Command A on a Mac). In the toolbar choose “Delete forever” to remove the files permanently from your Drive.