You can see some of the shortcuts for App Uninstaller next to the menu commands in application Main Menu.

Processing the Applications
Find applications and its service files for removal ⌘R
Select and delete specified application ⌘O
Reset the app to the state before first launch (delete app’s service files) ⌘⌥O
Show applications in Finder ⌘⇧O
Show information about selected application ⌘I

View Modes
Go into mode of Applications displaying ⌘1
Go into mode of Extensions displaying ⌘2
Go into mode of Remains displaying ⌘3

Applications Selection
Select all elements to remove ⌘A
Select service files for applications of selected by filter ⌘⇧A
Deselect marks from all previously selected elements. ⌘D