Step 1: What an empty roll looks like
You may be wondering to yourself, "How will I know for sure that there's no toilet paper?" The answer is that there will be a carboard tube on the holder with no toilet paper attached. You can be assured that there is no toilet paper there. This is what it will look like when the roll is empty. If it looks like this, then proceed to the next step!
Step 2: How the Toilet Roll Mechanism Works
Step 3: Removing the Empty Roll
The next part is apparently quite difficult, too, so bear with me. Find the nearest trash can or recycle bin and toss the empty cardboard container in there. (Again, see picture.)