Remove all the metal fittings, keel band etc first. Either treat these as scrap metal or hoard them! Locally I offloaded much of my hoard at a boat auction. When sawing up the fibreglass wear a face mask, particularly if using electric saw etc. I hasten to add that I never scrapped any of my N12s, I always found some idiot to buy them! I did scrap a very second hand tender I bought for £20 for my first post-N12 yacht. I sawed that up by hand using an ordinary panel saw.