fabmanager is going to be deprecated in 2.2.X, you can use the same commands on the improved 'flask fab <command>'
Usage: fabmanager [OPTIONS] COMMAND [ARGS]...

  This is a set of commands to ease the creation and maintenance of your
  flask-appbuilder applications.

  All commands that import your app will assume by default that you're running
  on your projects directory just before the app directory. They will also
  assume that __init__.py initializes AppBuilder like this (using a var named
  appbuilder) just like the skeleton app::

  appbuilder = AppBuilder(......)

  If you're using different namings use app and appbuilder parameters.

Options:
  --help  Show this message and exit.

Commands:
  babel-compile     Babel, Compiles all translations
  babel-extract     Babel, Extracts and updates all messages marked for...
  collect-static    Copies flask-appbuilder static files to your projects...
  create-addon      Create a Skeleton AddOn (needs internet connection to...
  create-admin      Creates an admin user
  create-app        Create a Skeleton application (needs internet...
  create-db         Create all your database objects (SQLAlchemy specific).
  create-user       Create a user
  list-users        List all users on the database
  list-views        List all registered views
  reset-password    Resets a user's password
  run               Runs Flask dev web server.
  security-cleanup  Cleanup unused permissions from views and roles.
  version           Flask-AppBuilder package version