How can I make a ceiling bulge disappear?

After a leak from a pipe I have a slight bulge in a plasterboard ceiling, how can I get it to shrink back?
John Ollerton, March 2011


done
Cut it out.
Only permanent way. You could use as many screws AS YOU LIKE, Plasterboard is now soft, screws will just go straight through

Sheepdog, March 2011