I don't know the Evolution but almost certainly it'll have either one or two circlips holding the wrist pin in place. If there's only one then the other end has a step in the piston so it can't move in that direction so take out the circlip and push the wristpin out that way. If there are two circlips then just take one of them out.

But that's getting ahead of things because there's something you'll have to do first seeing you've already got the piston/rod out of the engine. Assuming you haven't marked anything to know which way to put it all back together the same way (and you want the piston to go back in the liner the same way it's been running) then all is not lost, hopefully .

Almost all conrods only fit one way on the crankshaft so you'll have to look carefully at the bottom bush in your rod. One end of the rod will have a chamfer in the bush like in the first photo below and that goes up against the crankweb, in other words it faces to the front of the engine. The other end of the bush will be machined flat to the rod as in the second photo and that's the end you see when you take off the backplate. Find that chamfer and you'll know which way the piston should be so make a mark on top of the piston pointing to the front or maybe to the exhaust, whichever suits and that you'll remember. To the front is probably better because that's going to be the way the chamfer in the new rod will have to point.

Now you can take out one of the circlips using tweezers or very fine pointed pliers. I use tweezers with an angled end to get inside the wristpin hole more easily. But be careful because if it springs loose then you'll probably never find it again. Some guys take the circlip out with everything in a large plastic bag to catch it if it springs loose.

Push the wristpin through far enough to come out of the rod and then you can fit the new rod (put some oil in the rod bush first) making sure the chamfer goes the right way. Fit the circlip back into the groove with the tang pointing the same as it was originally but make dead certain it's right down in the groove.

Pistons and liners generally don't need to be cleaned other than a wipe with a very clean rag and some fuel just to make sure it hasn't picked up any dirt in the meantime. Rod bushes usually last quite a long time with the right oil so I'd suggest using a fuel that's got quite a bit of castor in it. There's no better lubricant for plain bearings or bushes than castor.