This could be because of leaks or overflows.
Rotten floor around toilet flange.
Insert the blade of the pvc saw into one of the holes then cut around the interior circumference.
Then install the new sub floor and glue on your new flange.
Cut support lumber usually 2x6s or 2x8s to fit between the existing floor joists on each side of the hole and install them with long screws leaving half the width of the support lumber under the existing floor.
Now is a good time to inspect the soil pipe and toilet flange for damage or wear.
Drill several large holes around the circumference of the toilet flange.
Remove the flange from the drain.
Flange support if you discover minor rot around the toilet flange install a closet flange support under the flange to transfer the weight of the toilet to solid wood.
Inspect to see if you can reuse it or if you need a new one.
Flush the toilet to empty the tank.
Remove the spongy flooring.
Sometimes the subfloor around your toilet will become soft and may begin to rot.
If you can t turn them cut the bolts just below the nuts with a hacksaw.
Lift the toilet off the remaining bolts and place on a tarp upside down.
If only the area directly below the flange is rotted you can install a two piece steel closet flange support.
The abs glue should break away and release the pieces.
Remove the two hold down bolts one on either.
Unscrew nuts from the bolts at the bottom of the toilet with pliers or a wrench.
Toilet flange is a pipe fitting that basically has two functions.
The first is that it connects the floor drain to the drain of your toilet.
Then use a hammer to drive a flat head screw driver in between the 2 pieces of abs flange and pipe.
Replace them if necessary.
You may need to cut it into more than 2 pieces to get it off.
Turn the toilet s water supply valve clockwise to shut off water to the tank.
Unscrew the flange bolts.