Help with caliper pin removal please

[G20RG B]

I am a bit of a numptie when it comes to car mechanics but I have decided to change the brake pads on my car myself
How do you get the caliper pins out? I can't get the pads out as the pins are holding them in.
Is there a special tool? I have tried hitting them out with a old allan key but it's just bent and I don't have anything else that fits.

Any ideas of helpfull advise would be great.

Oh and can you get callipers powder coated?

[G20RG B]

Thanks guys,

Ive soaked them in WD40 and ordered the tools that Mr2Mike suggested.

I'll give it another go tommorow.

George