This plugin allows NodeBB admins to approve new users. This is achieved by creating two new user groups, one for non-approved users and one for approved users and setting the category permissions accordingly. These two groups have to be specified in the plugin settings page of ACP for this to work.
Any new user is automatically added to non-approved users group upon registration. Admins can see a list of all new users in the ACP plugin settings page and then approve the users. Once the admin approves the new user, the user is then moved from non-approved group to approved group.
Installation
npm install nodebb-plugin-newuser-approval

https://github.com/pichalite/nodebb-plugin-newuser-approval