By default Spree uses the same model for the admin panel as the storefront. However you can customize it to use a different model. Let’s assume you have an existing AdminUser model in your application and you’re using Devise for authentication. In config/initializers/spree.rb file, add the following line: 
Spree.admin_user_class = 'AdminUser'
This will tell Spree to use your AdminUser model for the admin panel. You will also need to add the following line in that model file: 
include Spree::UserMethods
In your config/initializers/routes.rb file, you will need define devise routes for the 2nd model: 
Spree::Core::Engine.routes.prepend_routes do
  # Admin authentication
  devise_for(
    Spree.admin_user_class.model_name.singular_route_key,
    class_name: Spree.admin_user_class.to_s,
    controllers: {
      sessions: 'spree/admin/user_sessions',
      passwords: 'spree/admin/user_passwords'
    },
    skip: :registrations,
    path: :admin_user,
    router_name: :spree
  )
end
And now in your lib/spree/authentication_helpers.rb file, please replace the following lines: 
     def spree_admin_login_path(opts = {})
-      spree_login_path(opts)
+      new_admin_user_session_path(opts)
     end

     def spree_admin_logout_path(opts = {})
-      spree_logout_path(opts)
+      destroy_admin_user_session_path(opts)
     end
Now when attempting to access the admin panel, you will be redirected to the dedicated admin panel login page. Admin panel login page