I suppose you do not have the instruction booklet that came with the tractor.
If not, most of the Craftsman tractor decks are held on with a bunch of spring clips. They must be pulled out, and laid aside. Before starting, let the deck down all the way. On each side should be a long flat bar, wirh a pin and clip on each end. It is connected to the tractor, in its center section, by a loose adjustment bolt. Do not disconnect that center bolt. You will see two spring clips on each side bar, which runs fore and aft. At the rear of the deck there should be a flat bar that is connected to the deck at the inner end, and to a bracket from the left side of the frame.(Running cross-ways.) Remove the upper clip. There should be a round bar running toward the front, which is attached to the lever that puts the mower deck in gear. Remove that clip. The two round rods that go up to the front axle assembly have clips to be removed. There may be a smaller clip, on the front right side, in and up by the side bars, that may have to be disconnected, Just look in there carefully.
Do not unbolt the fore/aft pivoting side bars.
After you get it all disconnected, then pull the deck out, toward your right side, as you woul;d sit on the machine, then wiggle it out from under the tractor. It is kind of hard to explain it all. Thats why the tractor manual is very necessary for the job. Once you do 3-4 of them, it gets easier! HTH: Rusty Jones