There are a few things I would change about your code..
First - you have to close your tags...
<select name="name">
<option>text</option>
</select>
Then I would name each select box as the ID value(prefixed by S for select), and give the modify /amend as values in the options.
So, when the form is submitted,
foreach($_POST as $key=>$val)
{
if (substr($key,0,1)=="S")
{
if ($val=="Delete")
{
$drop="DELETE FROM category WHERE ID='".substr($key,1)."'";
$result=mysql_query($drop);
}
}
}
Something along those lines anyway...