they put it in a socket so no problems at all to remove it.
you have to get to your ecu which is located in behind your head unit/ashtray and all that. you access that area by removing the plastic kick panel in the footwell on the passenger side.
the ecu is located in a metal mounting bracket, unbolt it from that and pull the ecu out.. just remember its connected to the loom so it isnt going to go too far in a hurry.
you need a 10mm spanner to unbolt the loom connection. once you've fully undone it it will just pop off.
you then need to remove the 4 screws on the ecu that holds the top panel in (marked with a 39 sticker) or you could remove 3 of them and leave the 4th in as a swivel point for the panel.
then you need to remove the chip. to remove it safely without damaging it i highly recommened you go to dick smith, jaycar, tandy or similar and grab yourself and IC removal tool. basically its a little set of tweezers to remove your chip, make life a million times easier.
when you insert your stock chip ensure that the legs (pins) all line up with their sockets as they are pretty easy to damage/break off.
also, ensure your putting your chip in the correct way. there is a little notch in the chip (and there should be one in the socket too) you have the notch facing the same way on the chip as the socket.
if your socket doesnt have a notch and you didnt take note of how the previous chip was fitted you need to install it so that the notch on the chip is facing towards the centre of the circuit board.
if you need pics i'll post some to show you the way the notch should point.
hope that helps. if you can get photos that would be great & we'll faq it.
chances are though your problems have nothing to do with your chip. the information on the chip is hard coded and cannot be changed, maybe your car just needs a good tune up?