How can i reset the Content size of SPAN/DIV?

I hav elements inside SPAN, when user click RESET, i wanna reset the all contents... so what i need to do? Because im doing this:

var sp = new AW.HTML.SPAN;
var b1 = new AW.UI.Button;
b1.setControlText("01");
sp.setContent("01", function() {
  return b1;
}
);
var b2 = new AW.UI.Button;
b2.setControlText("02");
sp.setContent("02", function() {
  return b2;
}
);
var reset = new AW.UI.Button;
reset.setId("resetSpan");
reset.setControlText("Reset All");
reset.setEvent("onclick", function() {
  sp.setContent("01", function() { return ""; });
  sp.setContetn("02", function() { return ""; });
  sp.refresh();
}
);

I dont want erase content by content, i wanna do something like:

sp.setContentSize(0);
sp.refresh();

tkz.