Remove the Old Drywall
With the shelving out, and the old wiring pulled aside, remove the old drywall (Image 1). It is not difficult and comes off relatively quick.
Use a pry bar to remove the nails. The studs are toe-nailed into the base plate along the bottom. In order to have the new floor even, remove the base plate. First, remove the studs. Knock out the middle stud first so you will have room to work. Knock down the nails in the bottom plate with a hammer to keep accidents from happening. Be careful removing the last studs so that you do not damage any part of the wall you plan to keep. Cut the head with a reciprocating saw (Image 2) in order to reduce too much damage to the surrounding drywall.
Use a small pry bar to gently remove the old baseboards (in case you want to use them again). Once the baseboard is removed, use a reciprocating saw to cut the studs on the inside of the wall. Make a nice clean cut down the length the half wall and then remove it.
Drywall is a very versatile material and comes in 5/8th's thickness all the way down to 1/4". It can be bent, shaped or drilled. Corner beads are installed over drywall and need to be removed. Try not to destroy the drywall underneath.