How do I replace the sub-flooring in my bathroom

Please hire a pro.

remove all thats in the way of the floor and screw down new wood to the bath floor you willneed to make adjustments to accomadate toilet with the new height and doorway also thats the simplest less labor and does the job!

take up toilet

Use a circular saw that you can adjust depth. Saw a square. Take up the square - need be use a chisel.

In lay some plywood of correct depth - if need be shim with some wood shingles to make level. Now put on your new flooring

Real lazy - get some plaster - scrape away the rotted leak area - now plaster it level.

Smartest thing you can do is get a new Johnny ring - or go heir someone

I would not remove this subfloor.

Get 1/4 hardwood plywood available at Home depot & steel plaster lath that is available from any Drywall supply house in 28 inch wide by 95 inch long galvanized( perforated metal is what this is) about $6 a piece is the cost.

Sandwitch the metal lath between the hardwood plywood gluing the two together with a troweling of Polyurethane cement, use a ridge trowel about 1/8 high ridges. Then screw that to joists best u can with about #6 x 1 1/2 drywall screws.

Of course u can lift off the toilet, just remove those two bolts & up it comes.

You r asking for a major problem if u cut into this old subfloor. Every where u cut on the peremiter, u r going to form a non supported area that will squeal & be structurally inadequate even if u put in blocker blocks.

This sandwitch of hardwood plywood & steel lath will have an equivalent strenth far above anything needed to support a new floor. That slight 7/32 inch rise at door ways will be unnoticable if u tile & use an edge strip. Remember, that 1/4 inch plywood is actually 7/32 thick not 1/4.

I used a shortcut when I had this problem, I removed the toilet and removed all the rotten wood I could then used a fiberglass repair kit with glass cloth and filled in the bad places. May not work if your floor is badly damaged but on mine it was the area right around the toilet flange.
I did this two years ago and the flooring is still strong.

first disconnect the water supply line after you have shut off the valve..then flush the toilet.
next there are two plastic caps under the bowl..pry them off and right there should be nuts to the toilet bolts..take them off and pull straight up on the toilet..
if the floor is really rotten you may have to replace the toilet flange on the floor.not an easy job

This brings back nightmares. I do not know how many times I have done this!!!

Shut off the water to the toilet. Flush & bail until it is empty. Unhook the fill tube at the valve. Remove the bolts at the base of the toilet. (You might have to pry the cover caps off with a screwdriver or chisel.) If the bolts will not come off, hacksaw them.

Move the toilet out of the way. Sometimes putting a piece of cardboard in the tub makes a good place to place the toilet. Remove the floor with a saws all as far back as it is rotted. Sometimes u need to ''scab'' in support blocks for the new floor. This can be done with 2x4 is & deck screws. When replacing the floor around the pipe, put the ''split'' part of the board parallel to the wall. This will give u a solid area around the front of the toilet where the traffic is.

Cut ur replacement board, & then lay it on the floor & mark the floor to identify the small places that will need to be trimmed.

I am assuming that u have knowledge of carpentry, as there r 1,000 other details that I am leaving out. I am only putting in those that make a difference for the experienced handyman.

At the bottom of the toilet, there are 2 or more bolts and nuts that hold the toilet tight. They are usually covered by caps and you have pry the covers off, loosen the bolts, and lift the toilet straight up. You also have to disconnect the water line.

Tear out the subfloor and replace it, then get a new wax ring to seal the toilet, do not overtighten the nuts or you can crack the toilet. good luck. Had to do the same thing a few years ago.