Framing and Sub-Flooring - Bathroom Floor repair

A while ago I started a bathroom repair job after noticing the wall was "soft" below the faucet. Turns out the drywall was rotted away. This led to removing this stub wall and deciding to move the shower head to the other wall and putting in a synthetic stone wall system and glass walls and doors. Many other problems have been found but the current one is the floor had been wet and when I pulled up the vinyl floor the plywood tore up easily at the wall sort of like shredded wheat. The sheet extends 7' from this wall so I am assuming it extends 5 or so inches into the closet on the other side of the wall. Is there anything I can do to safely repair this floor without having to tear up the closet floor as well?

Welcome to the forums! If the water damage goes under the wall to the closet, I don't see how you can do half a job. On the other hand if the rot is limited to the bathroom, I would pull the flooring, and sheetrock back to studs, replacing the subflooring with new Advantech or similar product. Not sure what you will have as a final flooring, but if tile, you will need to install another 1/4" concrete backer underlayment. As for the walls, if they are tiled now, replace the sheetrock with 1/2" cbu and retile. Sheetrock has no place in a wet area, period.