To remove a template, search for the template and open it. This should bring you to a view similar to that below. Clicking the Remove template button will then remove the template.

This button will not be available if the template is currently in use. In this instance, the class using the template will need to be given a new template before the current template can be removed.

Admin users can now bulk delete templates and can see which lessons, teachers, rooms, and groups are using the templates.  More information on this can be found HERE