It is not possible to delete a DNS Template although all hosting plans that were using it are deleted.
The following error message appears when
Top > Service Director > Domain Manager > DNS Templates > Template name > Delete button is pressed
The DNS template is used by hosting plan(s) # and cannot be deleted.
Such behavior was classified as the software issue PBAS-21432 and will fixed in future OBAS releases. Please consider watching Odin public sources for information about updates in our products:
Knowledge base, each product update comes with a corresponding KB article.