If you're tearing everything out anyway, leave the tub for last. You may just have that 3/4" planking underneath that has gaps in it. If the tub is out, a lot of dust and debris will fall between the gaps. There SHOULD be clips holding the tub against the studs so these will have to come off, you will need to remove the drain basket using a drain removal tool or you can stick in the handles of a pair of groove-lock pliers and then use a screwdriver wedged between the handles for leverage. You will also need to disconnect the overflow as well. If there are no screws visible you'll need to pry off the cap to expose them, otherwise, just undo the screw(s). There will probably be a bead of caulking where the tub meets the floor, cut this out with a utility knife to make lifting the tub easier.Once all this is done, lift the tub up a bit at the opposite end of the drain first, this will loosen the whole thing and then just slide it out.