Many answers to the question already. For me the problem was two fold:
when I expand my routes:
devise_for :users do
get '/users/sign_out' => 'devise/sessions#destroy'
end
I was getting warning that this is depreciated so I have replaced it with:
devise_scope :users do
get '/users/sign_out' => 'devise/sessions#destroy'
end
I thought I will remove my jQuery. Bad choice. Devise is using jQuery to "fake" DELETE request and send it as GET. Therefore you need to:
//= require jquery
//= require jquery_ujs
and of course same link as many mentioned before:
<%= link_to "Sign out", destroy_user_session_path, :method => :delete %>