thank you
it work by using container.
what i did is:    select box and than make container and added text.
event 1 ) on start of layout, txt  set position  by object =  box
event 2 ) every 2 sec, create object = box on floor random x/y + make boolean "new" =  true
sub event ) if new = true , wait 1.5 sec set boolean new =  false.
event 3) if box overlap box + box new = true, delete box
by doing that i mange delete only the new  box+txt and prevent new box be created on top of other boxes.
but i dint understand how to do what you suggest with "UID"
"function to pick your squares to be deleted by UID"
can you pls show me how its done.