How can I disable overlayroot via ssh?
Solution 1:
You can run overlayroot-chroot to remount the root as rw, or bind-mount the lowerdir elsewhere as rw with something like mount --bind <lowerdir> /mnt/rootrw and modify on /mnt/rootrw (potentially chrooting to it if needed).
Check the link @Melebius gave, it (at least partially) answers the question.