Is there a simple way to remove popcorn ceiling?

Wet scraping (common method) Lightly mist the ceiling with water to soften the texture. Use a wide drywall knife or ceiling scraper to carefully scrape off the bulk. Most thorough, exposes a clean surface. Messy, may damage drywall underneath if too aggressive.

Rent the vacuum sander...saves you time and money and if used correctly very minimal mess

So, if the serface texture has previously been painted, wet scraping won't work very well but may still help depending on conditions of substrate. You may just have to scrape off as best you can with an 8" knife. Hard sand it with some 80 grit sand-paper. Then, it's a base double coat with two skim coats joint compound, sheetrock etc. Also have to repair whatever damage or cracks in the original drywall first. There are many ways to accomplish the desired finish after that...

If the ceiling has been painted, the standard water-and-scrape method often won’t work. Even on unpainted ceilings, sometimes more than a light misting is needed—apply enough water and allow about a minute for it to soak in before scraping. Vacuum sanders can also work well, but caution is essential: many popcorn ceilings contain asbestos. When wet, asbestos is not hazardous, but once dry and airborne it can spread throughout the home and create a lifelong health risk. If there’s any doubt, have a small sample tested by a professional asbestos testing company before starting. Google "Asbestos Testing". A final option, and one many contractors prefer, is to install new drywall over the popcorn. This is especially effective if the ceiling has been painted. It does require some drywall finishing skills, and many people dislike the process because tying into the walls means taping and then repainting everything. A helpful product called Tear Away L-Beads makes this easier—they cover the edges during finishing, then peel away to leave a clean line at the wall without having to paint or re-tape. Any stray drywall mud on the walls can be wiped off with water, leaving your wall paint intact and your ceiling looking new.