I can't help you with genuine official directions, but can suggest how to remove the crane from a Colt or Smith & Wesson double action revolver.
There's a screw on the right side of the frame in front of the trigger. Find a screw driver the exact size of the slot. If you use too small a screw driver, you'll probably mar the screw head in P.D.Q. order. Turn the screw counter-clockwise with firm, but gentle pressure. The aforesaid "screw" is actually a cap on Colt revolvers, but it works the same.
Tip the gun over to tap out the spring-loaded stop. If it's an old revolver that's been oiled half to death but never cleaned, it may be worth your while to squirt in some gun cleaner and let it set a few minutes if the stop doesn't fall out easily.
Release the cylinder latch and swing out the cylinder. Gently--and I do mean gently!--work the crane and cylinder forward. If you're not gentle, you'll scratch the cylinder against the frame and mar one or both. Better to spend a few extra moments and invest some extra wiggling with your fingers than mar the finish. Smith & Wesson cranes can be removed just by sliding them forward; Colt cranes are attached. Both can be further disassembled, but getting them back together and keeping all the bits and pieces properly assembled can be tricky.
I always remove the cylinder when cleaning a revolver, and put it back as gently and carefully as I removed it. I rarely disassemble a revolver more than that--except, of course, to remove the stocks before cleaning and replace them when I'm done.
Regards,
Standing Wolf