When I unpin the Result tab it hides but, when I run any SQL, it pins automatically and doesn't hide.
This is also true for SQL Plan and script outputs.
Basically for all tabs located at bottom.
RESOLUTION 1
Hit F2 to hide it again(this will probably hide more options that desired though)
RESOLUTION 2
Go to View | Toad Options | Editor | Behavior and uncheck "Restore unpinned panels on new data"