It's probably really easy to do but I don't want to put anything in there that will mess it up. Thanks

 

I just replace it when I replace the air filter. Pretty cheap. It's probably not dirty. It only gets used if the primary side gets plugged with snow

 

Personally, I have a spare. When I change air filters I pull the pre filter out and stick the one in thats waiting to go. I just use dish soap and running water to clean them. Wash until the water runs clean. When they start getting worn, I'll just get some replacements.