How to remove objects after it spawns...

I cant remove object (the “icon”, “icon2”) after it spawns

[lua]local mRandom = math.random
local mABs = math.abs

local objects = { “icon”, “icon2” }

local function spawnObject ()
local objIdx = mRandom(#objects)
local objName = objects[objIdx]
local ab = display.newImage (""…objName…".png")
ab.x = mRandom(40,300)
ab.y = display.contentCenterY

physics.addBody (ab, “dynamic”)
end

timer.performWithDelay ( 300, spawnObject, 3)

local btn = display.newRect ( 10, 10, 70, 70)
btn.x = display.contentCenterX - 50
btn.y = display.contentCenterY - -180

function removeicon (event)
if event.phase == “ended” then
display.remove ( ab )
end
end

btn:addEventListener (“touch”, removeicon)[/lua]