corona remove group

local myGroup = display.newGroup()

--Create 2 rectangles and insert them into 'myGroup'
local rect1 = display.newRect( myGroup, 0, 0, 40, 40 )
local rect2 = display.newRect( myGroup, 30, 30, 60, 60 )

myGroup:removeSelf()
--OR
display.remove( myGroup )

myGroup = nil