how to remove back wheel of my moped (peugeot 50cc)?

Living out in the country and getting a punctured rear tyre, a local agent quoted me £18 each way to collect and repair the moped.As this seemed rather a lot I was preparred to remove the wheel and run it in to a tyre repairer. I am new to mopeds and would like to know the proceedure for removing the rear wheel, which appears to be locknutted to the axle. also Does the exhaust assembly need removal too any help please. (the puncture was a thin flint in the crown of the wheel not slow enough to ride safely)