Sandbox wiki owner speaking here.
As a rule, the sandbox wiki falls under my direct control. I am moving to involve SCP wiki staff more in sandbox management, but for now I'm the only admin of the sandbox wiki. For the most part, I only delete pages that would not be allowed on the main SCP wiki; spam, advertisements, stuff for other projects, and unauthorized revisions of other user's material. Basically, if an admin tells you not to do something here, don't do it there either or I'll delete or edit it. That said, if anyone else is screwing with your stuff, that is a problem.
Additionally, the sandbox wiki respects the right of creators to handle the use of their material however they like. If someone uses your stuff, or mentions your stuff, or whatever, on the sandbox wiki, you are allowed to edit or remove that if you wish. That's primarily to avoid confusion about things like page status (In the past, pages have been accidentally rewritten without permission due to confusion. Check the discussion page for 103 for an example featuring me.), but also to prevent anyone getting their toes stepped on.
Beyond that, case by case basis. Because I'm the only admin and haven't hashed out who or what other moderative staff will happen, I'm not really comfortable laying down any specific rules. Talk to me if you have questions or problems.
All that said, I report to the rest of staff on anything at all SCP related. If an admin here tells me to do or not do something on the sandbox wiki, I'll honor their command as my superior. That's my way of ensuring I stay fair and nice and such, seen? I'm uncomfortable with absolute power. So if you as a sandbox wiki user take issue with something I do as owner, talk to me first, then to an admin, and together we'll figure something out.
Eventually, once I've herded a few cats, we will lay out a serious ruleset for the sandbox wiki, but until then, bear with me, because I mostly dunno yet either.
One thing I'm having trouble with is the fact that I do not know how to add discussion pages to the sandbox wiki yet. Because of that, it's custom among a few users including me to leave notes and commentary on pages in bolded, italicised, or otherwise stand-out-y text, so that authors or creators can have feedback on their work. Eventually I'll sort out the discussion pages thing…
TL;DR
The rules of the SCP wiki do not apply to the sandbox wiki. It will have full out rules at some point, but doesn't yet. We're working on it.