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    Q. -  what would be the best thing to  use to remove the paint and sealer off the floor a floor grinder or chemical it  is approx 4600 sq.ft and a restuarant
Hello Brett,
    A. -  The best  thing is to use paint strippers, glue removers, or Xylene. What helps the most  though is a stiff straw scrub brush like sold at www.ConcreteCamouflage.com.  It takes about 90% of the work out of stripping. Use painters shields as  scrapers because they're about 2' wide or wider which helps. Use square end  shovels and buckets to scoop it up and carry it out. You may need to go over it  a couple times. 
    You can use a good degreaser to help lift  it out of the pores of the concrete after stripping it if you  like.
    Once you've stripped all you can with the  strippers/removers, use a rented floor sander, like they use on wood floors, or  even a rented floor buffing machine with the sanding disks on it to lightly  sand it the rest of the way down to a good smooth finish and completely back to  concrete.
    Be sure and do a test in a closet or out  of the way place with the stain before doing the entire project. 
 I hope this helps.