To get at the filter in the tank physically, you must remove the tank. Siphon the fuel out of the tank or with a friend tip the bike over and empty the tank. Loosen, but don't remove, the bolt holding the tank near the carb. Remove the other two bolts and disconnect the fuel pipe. With the tank removed and the fuel pipe removed from the tank, insert a wood screw into the opening where the fuel pipe was, turn it a little to hook the filter and pull it out.
You can see the filter when the tank is empty or nearly empty by removing the cap and shining a flashlight inside. It is a little white plastic piece about an inch long.