How to empty/destroy a session in rails?

to delete a user's session

session.delete(:user_id)

session in rails is a hash object. Hence any function available for clearing hash will work with sessions.

session.clear

or if specific keys have to be destroyed:

session.delete(key)

Tested in rails 3.2

added

People have mentioned by session={} is a bad idea. Regarding session.clear, Lobati comments- It looks like you're probably better off using reset_session [than session.clear], as it does some other cleaning up beyond what session.clear does. Internally, reset_session calls session.destroy, which itself calls clear as well some other stuff.

To clear the whole thing use the reset_session method in a controller.

reset_session

Here's the documentation on this method: http://api.rubyonrails.org/classes/ActionController/Base.html#M000668

Resets the session by clearing out all the objects stored within and initializing a new session object.

Good luck!