We were going to replace toilet bowl and tank when we discovered that the toilet bowl is seated on cement. How do we remove toilet bowl without breaking it? Thanks.

Personally I would remove the bolts at the bottom, may be called flange bolts, turn off and disconnect the supply line, and apply side pressure to break free. Should break free with little or no effort.

Some old plumbers used to sit toilet bowls into bed of mortar or concrete. It is almost impossible to remove the bowl without breaking it. But I've done it few time with satisfactory results. Try to take a sharp, skinny, chisel and very carefully keep chipping away around the base. You may get it loose enough to remove the bowl w/o breaking it.