How do I remove the Devise route to sign up?

I'm using Devise in a Rails 3 app, but in this case, a user must be created by an existing user, who determines what permissions he/she will have.

Because of this, I want:

To remove the route for users to sign up.
To still allow users to edit their profiles (change email address and password) after they have signed up

How can I do this?

Currently, I'm effectively removing this route by placing the following before devise_for :users:

match 'users/sign_up' => redirect('/404.html')

That works, but I imagine there's a better way, right?

Update

As Benoit Garret said, the best solution in my case is to skip creating the registrations routes en masse and just create the ones I actually want.

To do that, I first ran rake routes, then used the output to re-create the ones I wanted. The end result was this:

devise_for :users, :skip => [:registrations] 
as :user do
  get 'users/edit' => 'devise/registrations#edit', :as => 'edit_user_registration'
  put 'users' => 'devise/registrations#update', :as => 'user_registration'
end

Note that:

I still have :registerable in my User model
devise/registrations handles updating email and password
Updating other user attributes - permissions, etc - is handled by a different controller

Actual answer:

Remove the route for the default Devise paths; i.e.:

devise_for :users, path_names: {
  sign_up: ''
}

Solution

I tried to do this as well, but a thread on the devise google group dissuaded me from searching for a really clean solution.

I'll quote José Valim (the Devise maintainer) :

There isn't a straight-forward option. You can either provide a patch or use :skip => :registerable and add only the routes you want.

The original question was :

Is there any good way to remove a specific route (the delete route) from Rails?