for(int i=0; i<4; i++){
     List<Object> sub=new ArrayList<Object>(prevoiusList.subList(0,6));

     for (int j=0; j<6; j++){
         previousList.remove(j);
     }
}

previousList = previousList.subList(7, previousList.size());

List<Object> list;
List<Object> subList = new ArrayList<Object>(list.subList(0, 6));
list.removeAll(subList);

List<Object> list;
while (list.size() > 5) {
    List<Object> subList = new ArrayList<Object>(list.subList(0, 6));
    list.removeAll(subList);
    // do something with subList
}
// list now has 0-5 elements

prevoiusList.subList(0,6).clear()