Can you tell me what is supercedure.
Supercedure is where the bees replace their queen, without increase in colony number, as opposed to swarming which should lead to another extra colony (or more) being founded (super organism reproduction).
is this supercedure ?
Don't know. Could be either supercedure, swarming or emergency requeening.
The number, position and shape would help to determine the reason for the queen cells, as would the conditions within the hive. Supercedure cells are usually few, on the face of the comb and acorn-like, a little away from the comb. Swarm cells are usually easily recognised, once experienced and emergency cells will have other attributes. Several years old for a queen is 3 or 4.
do I kill her and let the hive make a new queen
No, they will do that job later. Bees are perfectly able to do that. The only time a beekeeper intervenes to kill a queen is on quality and when fully able to get her replaced, normally by introducing a new queen or by uniting two colonies (which usually amounts to the same thing).
do I get rid of the queen cells as I have in previous years.
'In previous years' you say yet claim to be (quote) 'a new beekeeper'. So this is at least your third season?
I really think you should get your books out and read them again.
do I try and create a new queen
The bees can do this much better than you. They have been doing it for many millions of years, so much better than you at it.
RAB