I know this is an older post but I ran into the same thing (kinda) and here is what I learned:
1. If you need to remove Octane data, hacking the PZ3 will definitely work, but a much easier way is to invoke "Remove all Octane data" (or something like that) menu option in the scripts pull down menu in Poser (not the render engine, but the Octane menu where you can convert lights, etc. Works great everytime.
2. I have moved Poser/Octane to a new computer twice now and the first time I burned alot of bytes on this forum with the same questions. No easy answer then. Orginally my runtime and Octane directory (where I keep all my HDRI lights, Redspec files, etc.) were split across two drives, C: and D:. My 2nd system I was using D: and E: drives and previously created content with the plug-in was a nightmare to realign to the new drive and that poser search window got a serious workout. I found it was easier to use option 1 above and just start over. Newly created and saved scenes were no problem just previously (pre-2nd computer) saved scenes.
THIS TIME I simply put my Octane content directory directly in poser's runtime directory and it works seamlessly 95% of the time. Not PP11's directory, but the HUGE runtime I have been working with since Poser 4! Not sure why this worked so well, and I don't really care...it works.
Hope this helps someone out there...
i7 6800K (6 core), 24 GB, GTX 1080 8gb, Titan X 12gb