Remove part of url

Hi,

I'm trying to remove the last part of an url, when a dropdown is changed, that looks like this:
edit.php?do=delete&id=x
The "X" needs to be replaced.

The code is use is:

$('#delemail').attr('href', function(index, attr) {
	var url1 = attr;
	url = url1.substring(0, url1.length - 1);
	return url + foo;
});

Select allOpen in new window

But this only removes the 'X'. So the first time it works fine, but if the "X" is replaced with an id, like 233, and the dropdown is changed again, the id will be: 23XXX

How do i completely replace the whole id onchange? (no matter how long the id is)

Thanks