I have a global variable for my proxy, see url below, and that works great, but I wanted to test installing without a proxy so I used the override, emptied the string and then noticed the generated template still contains proxy=http:// etc.

The override should be able to unset a variable as well, I think.

https://github.com/theforeman/community-templates/pull/388/commits/08ef1647069cdd16a1155b830f8171049a13e02b