Add <Delete> Element to <Update>

[cleder]

<Update>
  <targetHref>...</targetHref>    <!-- URL -->
  <Change>...</Change>
  <Create>...</Create>
  <Delete>...</Delete>
</Update>

https://developers.google.com/kml/documentation/kmlreference#example-of-create https://developers.google.com/kml/documentation/kmlreference#example-of-delete