[turker]

function log_out(){
 if (confirm(Silmek istediğine emin misin ?')){
  window.location.href='action.php?act=sil&id=2';
 }
 else{
 return false;
 }
}

<input type="button" value=" Sil " name="sil" class="kabul" onclick="return log_out();">