I would encourage you to look on Youtube for how to remove it. From what I’ve seen, if you get it wet/moist/steam it, it scrapes right off. It actually looks like it would be a fun and satisfying project.
I think that my brother did it the way leamk is suggesting. Spray bottle (garden sprayer) and spackle knife or large scraper. just make sure to check that popcorn doesn’t have any asbestos.
Some friends learned last year the popcorn in their early 1960s apartment has asbestos in it so be careful. Naturally they have already lived there over 7 years and as a bachelor pad there have been plenty of stray darts, footballs, and other sports equipment that have bumped the stuff before they knew.
Get it tested for asbestos! If it is asbestos don’t do the work yourself, get a licensed abatement contractor. Laying rock right over the popcorn may be less costly, though.
February 2014 I had my dining & living room popcorn ceilings tested – both contained asbestos. We were planning to remove ourselves, but after watching many DIY videos, decided to bid the job. Got a couple bid, and used Affordable Environmental http://www.affenv.net/ – Not in West Seattle, but completely satisfied with their amazing job prepping the rooms & managing air quality.