Board Thread:Support Requests - Community Management/@comment-72.235.10.69-20150518121408/@comment-1038387-20150518122352

Send that user a message on their wall/user talk, in English, explaining that your wiki is an English language wiki. They can create their own wiki in their native language if they wish.

If they reply in Spanish, use Google Translate to understand that reply. It's not 100%, but should get the general gist across. Reply, again, in English.

Also, you're free to delete that page if you want.