The closest option for ignoring vocabulary you don’t need is using the lesson picker they’ve soft launched a few weeks ago. It’s going to be a permanent feature when they finish working on it.
This is your best choice for communicating with WaniKani staff directly about your issues with specific content you want to add/change/remove.
There are indeed several, this is used only in official document, or that you don’t use it for speaking it exist only in writing. So it would probably help if you point out such vocabs specifically , so they’ll add that caveat.