changing carpet

'91 Nissan P/U... Would like to change carpet. How are the rocker panel moldings (in the door jamb) removed? It looks like they are secured with plastic rivets. How are the rivets to be removed / replaced?
Thanks,
Ray

They will most likely fall apart from old age make sure to take one out got to an auto parts store and order new ones, this things always go, no saving them.