Demolishing large concrete patio slabs
What you have is a concrete slab  not a block. Semantics.  I would rent a jackhammer, breaking that thing up with a sledgehammer will be a arduous task.  You may also need an angle grinder with a metal cut off wheel to cut the metal lath or rebar reinforcement’s that should be inside the slab.  You will want to break it down into small enough pieces to lift and handle in order to make the disposal job easier.