Is there any way to prevent local user registration?

[panjie]

That is to say, even registered in local wiki, the user will be global user.

[tmortagne]

There is no way at main wiki level to do that, you have to disable it in each wiki: the way to disabled registration is by removing register right from “Unregistered users” or by explicitly giving it to XWikiAllGroup for example (which will remove it from “Unregistered users” if it does not already have it).

[evalica]

When you create a new wiki, you can select in Step 2, in the ‘User Scope’: “Only global users are available in the wiki”. After creation the selection for the wiki can be seen in Administration > Users.