Does kafka streams clean up its state store on rebalance, or simply accumulate them?

I wonder what happen to state stores when there is a rebalance in a kafka-streams application. Let say an instance goes off for a while and then comes back, either out of the static membership time window, or with no static membership at all. Does the old state store corresponding to the old tasks assignment gets deleted or do they live there together with the new state store corresponding to the new task assignments ?