[{"Blocks":[{Name:"HouseKeepingDamageCost",Periods:[{Type:"Past",IndividualAge:65},{Type:"NOT Past",IndividualAge:65},]}]},]

db.collection.update({},{"$unset":{"Blocks.$[block].Periods.$[period].IndividualAge":""}},{"multi":false,arrayFilters:[{"block.Name":"HouseKeepingDamageCost"},{"period.Type":"Past"}]})