Well you activate it (hold down CTRL+SHIFT+C to see a grey box appear top left, type "move_objects on" and press enter) and then go into Build or Buy mode and use the Hand object.
With this cheat you can select and delete anything on the lot including Sims - however please take note of my article on thesimszone.co.uk (click
here) for what not to delete.
Otherwise with the cheat, its useful for getting sims out of traffic jams for example, or making space in the bathroom when hundreds of sims decide they all want to use the same toilet.