Guest Mode in previous Ubuntu versions was vary useful yet, in 17.10, one gets Standard or Admin. We need Guest mode for several reasons. I have not been able to discover a Lockdown-ClearOnExit Guest Mode solution in 17.10 and therefore use older version - not good. If there is a place to vote on Guest Mode return to 17.10 and/or future versions - count me in. If someone has a solution - please post.
This subject is fully covered in https://community.ubuntu.com/t/guest-sessions-in-18-04-lts-are-they-needed/1714
Your question is half complaint and half help request, not site feedback, so I’ve moved this to the https://community.ubuntu.com/c/support-help-requests category because this site isn’t designed to take tech support questions. Sorry. I’d recommend using one of the official support channels listed on the https://community.ubuntu.com/t/finding-help/712 page.