netbox/netbox/templates/utilities/object_set_field_null.html

{% extends 'utilities/confirmation_form.html' %}
{% load form_helpers %}

{% block title %}Clear {{ field_human_friendly_name }}?{% endblock %}

{% block message %}
    <p>Are you sure you want to clear the <strong>{{ field_human_friendly_name }}</strong> on {{ obj_type }} <strong>{{ obj }}</strong>?</p>
    {% block message_extra %}{% endblock %}
{% endblock %}