Sometimes there is a need to disable "Create new account" function. Should be easy to implement.
This was implemented a while ago. My mistake, there is a setting to enable manual user activation, the admin has to approve the account.
I think it'd a good idea to create a topic listing all the features Spirit has right now
Register by invitation only can be a new feature.
So what's the setting to enable manual user activation?
There is none, that feature does not exists. See this issue