When an Administrator try to reset scoreboard for a Role it will give an error "This action is not permitted for Role Scoreboards". Why cant a Admin Reset scoreboard for a Role?
This is by design.
Scoreboard can be reset only by the logged in user and it cannot be done for a Role.
Hence the users need to reset their scoreboard individually from customize scoreboard web page where they can click reset button.
There is no Global reset because individual custom scoreboard will be lost.
On clicking Reset Tree button all it does is resetting the contact's User_Query entries to that of their Access Type's entries.
So if the Role Scoreboard was to change again after the Reset Tree, the contact would not see the new changes.