Doc:
{ _id: 5150a1199fac0e6910000002, name: \'some name, items: [{ id: 23, name: \'item name 23\' },{ id: 24, name: \'ite
try..
db.mycollection.update( {'_id': ObjectId("5150a1199fac0e6910000002")}, { $pull: { "items" : { id: 23 } } }, false, true );