Put on sturdy work gloves to protect your hands and goggles to protect your eyes.
Swing the sledge hammer against the sides of the double brick wall, aiming for the joints of the brick where you see mortar. You want to aim for the joints where the mortar connects the bricks because the mortar usually will break apart more easily than the brick. Swing forcefully, ensuring no one is behind or beside you. Swing the sledge hammer on both sides of the wall. If the brick does not break easily, move on to cutting the wall down with a saw to loosen it.
Pull the bricks off the wall as the mortar and bricks begin to crack.
Cut through remaining, stubborn bricks with a cut-off saw. Put on a respirator before starting the saw. A cut-off saw is strong enough to cut through hard materials, such as concrete and brick. In some cases, you might need to cut just a portion of the wall to get the demolition started. You then can knock down the bricks more with the sledge hammer.