The Access Levels View gives an overall picture of what access has been granted to which users.

The Access Levels view shows an entry for every access record that has been granted. Each entry specifies the person or group for which access has been granted (shown in the Name column) and specifies the folder, user or group to which the access has been granted (in the Access To column) and specifies the level of access granted (in the Access Level column).
The Access Levels View does not show the effective access for a user, so in order to view the effective access for a particular user, you must look at the User Details View. For example, if a group has been given access to a particular folder, there will be just one entry, rather than an entry for every user belonging in the group.
The Access Levels View is useful for withdrawing access that you have granted. To withdraw access, simply select the relevant access entry and press the Delete key. The administrator will ask to confirm that you wish to delete the selected item(s).

Pressing the Yes button will withdraw the access.