Press down firmly around the perimeter of the click wheel to separate it from the adhesive securing it to the outer case.

This requires a good amount of force. Work slowly.

It may be helpful to use an edged tool to separate the adhesive from the click wheel on the inside of the Nano while pressing it down from the outside.

Remove the click wheel from the inside of the Nano.

Be careful not to let the click-wheel slide on the metal plate supporting it, as it will break the flat cable. Apply force perpendicular to the click-wheel.