just punch it with any thing like a nail small screwdriver ect it comes out easy but you must check how it is tapered and make sure you punch it from the right side
I bought full allen key set rom my local hardware/diy store, full set of metric and imperial £3.99. Check out your local wickes/b&q, homebase or Halfords I'm sure you'll get what you need.
...or Poundland. Iv had a 20 piece set from there AGES ago, and they're still straight as the day i got them (havn't rounded off) PLUS, they were only a quid!