All In One Desktops

Pretty much what the title says. I’ve had my computer for nearly a year now, and while it’s still a fast runner and kept clean with antivirus, etc, it’s been making some strange little noises whenever the cooling fans start up. Obviously, I assume it’s down to the fans being a little dusty; but considering that I have an all-in-one desktop PC (Advent) there doesn’t seem to be any way to carefully and delicately open it up and clean them myself.

So…how does one get the fans cleared out from this thing? :/