Cannot select Curtain system

[dcnkzr]

I have created a generic model then create a custom curtain system by selecting four feces of  that generic model .Idont know for what reason one of this wall(cutain system) had been disassociated and cannot select as a system just can select curtain panels and also cannot delete tehse panels .I dont know what to do.I would like to slect and delete them then recreate curtain system

[barthbradley]

Maybe it's Pinned and you have Select Pinned Elements unchecked in the drop-down dialog under Modify.