It depends on what they actually used for texturing, and if they put a coat of paint over it. Stuff like ceiling texture will usually soften if you wet it, and then, it's fairly easy to scrape off if it wasn't painted over. If they used a cement based stucco material, wetting won't do much of anything.
Should you try to sand it off, make sure to wear LOTS of protection for both your body, especially eyes, and lungs, as some of the stuff could contain silicon, and that can be carcinogenic in dust form. Regardless, it will make a mess, so dust collection is mandatory and cleanup will be a pain.
I'd see if it softens when wetted, and then, scraping it off is fairly easy. I did the ceilings of about 500sq in a few hours by using that method. I couldn't do that today as I am a lot stiffer, and working over my head isn't a real choice. On a wall, though, shouldn't be an issue if it softens when wetted. Using a spray bottle, get a section really wet, then wait maybe 10-minutes...you'll know by then if it can be scraped off.
1/4" drywall will follow some of the peaks and valleys of the texturing...IOW, it will be hard to keep it nice and flat. 3/8 or 1/2" would have a better chance should you decide to cover it up.
Or, if it was done over drywall, you could tear the old stuff out and put up new then paint it easily...maybe less work, but you'd have more stuff to cart to the dump. Drywall is pretty cheap. How much is your time worth?