MuseScore --
Index
-- Brackets
Remove
Select the bracket and press <
Del
>
Add
Drag a bracket symbol from the bracket palette to an empty space in the first measure of a system.
Change
Drag a bracket symbol from the bracket palette to an bracket in the score.
Edit
Double click on a bracket to enter
edit mode
, In edit mode you can drag the hight of a bracket to span arbitrary staves of a system.