The Popit Menu is the most important tool you'll come across in the world of LittleBigPlanet - press the Square button and it'll literally "pop" into the air above your Sack person's head. Think of the Popit Menu as an interactive lasso that's capable of amazing things: it contains almost all of the creative options at your disposal.
The Popit Cursor allows you to pick up a shape you've created, so you can do a variety of things with it: move, duplicate, delete, resize, or detach (in case it's glued to something).
To use this tool, you first need to select Popit Cursor from your Popit Menu (Top left corner).
Hover the popit cursor over an object and select it with X..