If you want it closed, Fandom will get around to that eventually. If you want to expedite the closure, just contact staff. Otherwise, you could use it as a test wiki but then the name might be an issue. Staff might be willing to move it or they might just close it and tell you to open a new wiki as your test wiki. I am not sure which they would do. The last option I can think of is unlikely but, if there is a topic that could use the same name and you are interested in, you could repurpose the wiki.