This API will delete all plug-in settings and most (possibly all) camera settings. I don’t know about the stitcher.
You can achieve a deeper level of reset (which will also delete all images) with Vysor
Your camera needs to be unlocked to use Vysor.
You can unlock your camera here:
https://www8.webcas.net/db/pub/ricoh/thetaplugin/create/input
Please back up your data and write down any critical settings.