A lot depends on what the texture is made of. The best way to get rid of popcorn ceiling is to spray the ceiling with water (not too much)let the water soak for a few minutes and then scrape with a dry wall blade. You don't want to penetrate the paper of the dry wall...this would require more mud and sanding. Usally textured ceilings aren't finished as well as walls so removing the texture highlights all of the imperfections of the original job...thus openning another can of worms...if you try the H2O be careful not to over wet the surface...too much water and your putting up new drywall. More then likely the texture was drywall mud which will probably difficult. I have also sprayed a heaver amount of mud and knocked down with a drywall knife for a deeper more uniformed texture...it is easy to do but if you have never done it before hire a pro.