How Do I Take Out A Ceramic Tile Floor?

A pair of safety goggles very important, porcelin shards will fly everywhere when you're doing this and almost certain that ignorance without safety goggles is most sure to have it's reward. Use a cold chisel about 1 inch wide you can get anywhere, yes it's important that it is a cold chisel not a wood chisel. And a pair of those $2 dollar raw hide garden gloves is ideal to protect from slipping your hand down the chisel after a while of doing the same old thing for a long time straight, and the slip up of a chance of your hand accidentally sliding down the chisel into a chipped piece of tile. Use a cold chisel and a regular hammer and that's all you need to remove an entire tile bathroom / any room. It's hard on the knee's after awhile so use a pad or knee pads as you see fit. I'd grab a large rubber barrel to get the jist of the garbage out of there but that stuff gets heavy in small amounts so use perseverance with that however you chose to deal with it. 1 last thing about the uneven surface under the tile you removed. Two choices which can easily be controlled if you keep it simple in your mind and in action to level it out. All of the grooves in the glue cement are made by the glue trowel which is how the tile is applied an / or reapplied. . If you just laid an entire flat layer of glue on the bottom of a piece of tile it would not hold as well as a piece of tile that you use a grooved trowel to smear it with, it allows space to press the tile down into place and adjust it more easily afterwards, those groves also allow upward and downward movement as well as left to right movement to slightly adjust them. Get a bag a CROSS spacers when reapplying so the job is easy to align them when you reapply. But to LEVEL THE GROOVES when you remove the tile to build again you either ( 1 ) spend a couple hours with your cold chisel doing the pain staking work of hitting down any high points in any of the thousands of grooves going across the floor your working on or ( 2 ) Chisel off quickly any few high points of any severely high grooves that are sticking up too much to get a base level floor again before putting a new sheet(s) of 1/8" Lewon Plywood or 1/4" sheet(s) of plywood and screwing the sheet(s) down every six inches square with 1 1/2 to 2" drywall screws across the entire floor and then building off the new CLEAN plywood. Your choice.

You can rent an electric hammer chisel from Home Depot or a rental supply store to remove the old tile with. It is so much easier and worth the rental cost which is around $40.00 to $50.00 for 24 hours depending on where you rent it from. So call around for the best price. You don't have to get on your knees to chisel the tile off, because the tool is an upright.
  If your sub- floor is concrete you will have very little problem with this method. The hammer drill/chisel will also remove the old thinset mortar from the floor. Would make sure that the floor is level before installing the new tile. If it isn't use the self leveling compound before laying the tile. Just be sure to let the compund dry/set up before tiling.
If your sub-floor is wood or plywood, recommend that it is in good shape. If so, then you can purchase the self leveling compound from a home supply store. Pour it onto the floor and skim the surface of the wood. Once it drys, you can apply the thinset over it for a much better bond.
If your plywood floor is in bad shape, recommend that you replace it with 3/4 inch plywood, then skim it with the leveling compound.
As Prosumer said, always wear safety goggles when removing old tile and a long sleeve shirt.