I sold one recently, not as big as that, about 25m single glazed lean-to type. Put an add in buy and sell and had plenty of calls on it. Agreed a sale and the guy who bought it came out with a long trailer and four of us took it down in half a day.
If you can, leave it up until the buyer comes to take it down as it is handy if they can number/label the pieces for re-erection.
Dont expect too much money for it, just be glad to get rid as sending it to a tip will cost you money.