Delete Term via edit-tags.php

"<a class="delete-tag" href="" . wp_nonce_url( "edit-tags.php?action=delete&amp;taxonomy=$taxonomy&amp;tag_ID=$tag->term_id", "delete-tag_' . $tag->term_id ) . "'>" . __( 'Delete' ) . "</a>";

$tag->term_id

It’s exactly what it says, where did you define $tag?
Also, I’m assuming $id is the $tag->term_id, so you might want to use $id instead.