I assume you are looking for instructions for removing the crossbar from the boat, not disassembling the crossbar itself.
To remove the crossbar from the boat, it's easiest to do this with the boat on the trailer and each hull strapped to the trailer to help hold it in position after the crossbar is removed. The first thing you will need to do is unlace the tramp completely and then slide each tramp half out of the tracks which run along the inside of each hull. You will need a 5/16" hex wrench (either an allen wrench, or a hex bit socket so you can use a ratchet wrench) and a 9/16" socket wrench. It's also handy to have a pair of vice grips available.
There are eight bolts which hold the front and rear crossbars to the hulls (an inboard and an outboard bolt at each corner). Use the 5/16" hex wrench to loosen the inboard bolts. The bolt heads are located under the lip on the inboard side of the hull at each of the crossbars. Loosen each bolt a few turns. Then use the 9/16" socket wrench to loosen the outboard bolts. If the nut on the bottom of the outboard bolt turns when loosening, hold it with the vice grips. Once you've loosened all eight bolts a few turns, then go back and remove all four front crossbar bolts (inboard and outboard). The front crossbar will lift right off the hulls.
Installation is the reverse process. When installing the crossbars, it's best to get the inboard bolts started first as they can be difficult to line up properly. You may want to have a helper assist you by holding up the crossbar and lowering it down onto the bolt. Be very careful not to strip the threaded insert inside the crossbar when installing the inside bolts. Once you have the inside bolts started, get the outside bolts installed loosely and gradually go around tightening all the bolts incrementally. It's also important to use anti-seize grease on the inboard bolts, otherwise they could seize in the threads.
Once the crossbars are installed, re-lace the tramp. After the first sail, go back and check all the bolts are tight and you're good to go.