Start by sliding up the bottom sash and tilt it towards you. Release the tilt arms using a edged object such as a screwdriver. To release the tilt arm place the edged object between the spring clip and the black button. Repeat the instruction on the other side. Now push the sash back into its upright position. Release the sash from the brackets found underneath the bottom sash by unscrewing the screws. You should now be able to carefully lift off the bottom sash.