Cluster rebuild

Hi. We have 7 Nodes in our cluster, of which 4 nodes were reimaged due to corrupt filesystems and could not complete  smartfail earlier. Post reimaging and joining to cluster, there were 2 entries for each of the 4 nodes - one in OK and one in down. Hence cluster lost quorum since 50% Nodes were in Down state and 50% in OK stae, and it went into RO mode. My question is the below:

1> Is there a method to delete the extra entries for those 4 nodes that are still showing as down?

2> Is it possible to reimage the Node when the Nodes are in RO mode? If yes, then how?

3> Is it possible to destroy the whole cluster? If yes, please share the procedure.