While a wiki founder may request that their project be closed, particularly if it doesn't yet have any other editors, if the topic is of general public interest Fandom generally prefers to leave dormant wikis available for adoption by new users.
Wikis that remain inactive for several months, without any interest in adoption, may be merged or closed by Fandom Staff, but there is no urgency or set schedule for doing so, since inactive projects do no harm to active ones.
If some or all of a wiki's contributors decide to move, and copy the content to a new a location, Wikia, Inc. will decide whether the wiki is to be closed or whether it will remain open as before. Most wikis with useful content or the potential for content remain open. As a courtesy to future editors and to the Fandom staff involved in deciding if the wiki in question is to be closed and/or merged with an existing wiki, please do not blank pages or list them as "Moved" (especially the main pages).