Remove all furniture and other items from the room. Cover up the floor with painter's plastic. Use the painter's tape to tape the painter's plastic to the floor. Removing the popcorn ceiling is a messy process, and covering the floor makes cleanup easier.
Score the edges of the ceiling with the utility blade to prevent damaging the walls when you remove the popcorn texture.
Fill the pump sprayer with water and pump it with pressure.
Spray the popcorn ceiling with water using the pump sprayer. Do not be afraid to soak the popcorn texture. The more you wet the ceiling, the faster the popcorn texture will come off. Let the ceiling absorb the water for 10 minutes. Spray another light coat of water on the popcorn ceiling. Refill the pump sprayer when you run out of water.
Scrape off the popcorn texture with the spatula. The texture should start coming off when soaked with water. If it is still hard to remove, keep wetting it with water until it starts scraping off. Use a wide metal spatula to finish faster.
Remove the painter's plastic and throw out the popcorn texture. You need to let the ceiling dry for 48 hours before applying compound and painting it.