Turn the main water supply off by turning the ball valve at the sprinkler manifold 90 degrees.
Locate each sprinkler head on your system. You can insert a pencil into the ground next to each of the heads to mark their locations for reference.
Dig around the area of each sprinkler head, exposing at least 7 inches of dirt around each base. This will expose the entire sprinkler body and show which direction the pipe goes.
Unscrew each sprinkler head counterclockwise to remove them from the risers below. What's left is the riser and supply line.
Dig a trench along the path of the underground pipes to expose them. Follow the path of the supply lines from sprinkler head to sprinkler head, and finally to the manifold at the irrigation control box. Clear at least 7 inches of dirt around the pipe the entire length of the system.
Cut the pipe every 8 to 10 feet, ending at the manifold box. This will make removing the pipe easier.
Pull out each section of pipe and discard.
Dig around the base of the manifold control box to expose the edges of the box.
Lift the box up and discard it. You should have the manifold exposed at this point.
Cut the supply line from the house to the manifold, leaving at least 5 inches of pipe exposed on the outside of the house.
Pull out the manifold and discard it.
Place a push-to-fit pipe cap over the end of the exposed pipe. The cap will automatically seal itself and prevent water from leaking. Turn the main water back on at the ball valve and check the cap to make sure it's on tight.