In Google Chrome there is an easy way to see what's in local storage as well as modify or delete it after inspecting it.
Is there a way to do the same in Firefox?
You can delete localStorage items one by one using Firebug (a useful web development extension) or Firefox's developer console.
You can enter these commands into the console:
localStorage; // click arrow to view object's properties
localStorage.removeItem("foo");
localStorage.clear(); // remove all of localStorage's properties
Firefox now has a built in storage inspector, which you may need to manually enable. See rahilwazir's answer below.