I forgot to update this. I went back the next day and finished up. I had to go slow because I was working near the electric service triplex.
Amazingly, the flashing and sealant had held up, so there is zero rot or damage to the wall of the existing structure. All of the rotten stuff is gone and the porch is ready to be rebuilt. I will leave it up to the rebuilders as to whether or not they want to remove the sides. I would myself, but that is between the owner and whoever rebuilds the roof.
The porch was installed new in ~1975. The building is is a late 1700’s(?) log cabin that was disassembled and rebuilt at a new location in ~1975.