They are push pins. Squeeze the end the push them back out.
You wouldnt know how to remove the front fan and filter would you?
I didn't but I do now! I found my old case in my garage (this post was 2 years old good job finding it!). Ok, the easy part is I didn't see a way to remove the filter so if you need to clean it just blow a bunch of air through it.
The fan takes a bit of work. You have to remove the front face which will feel like you are breaking it but you aren't. It's held on to the case with 6 big push pins. The problem is all your wiring is right there for the esata and usb ports. You also have all the wiring on top for the temperature display. Unhooking all of those is a pain, but you can work around it. Once you have the face off the fan is held together by 4 Phillip screws. Easy enough to remove those. The hardest part is getting to your fan. You have to remove the hard drive bay. That is held together by two small phillip screws inside the case and then two more screws on the bottom of your case. You'll probably have to take your motherboard out to move the hard drive bay far enough to give enough clearance to get the fan out. Let me know if you need any additional help. I can take pics of it too if that will help.
Edit: Oh and you might have to remove you drives (dvd/bluray/card reader) in order to get the face off or put it back on. For me it came off fine but wouldn't go back on unless I removed them and then put them back in after the face was on.