Upfront Child Theme Builder

Hello,

As I was busy creating a child theme for a website, I stummed upon an issue with getting posts on my postpage. Now that problem is solved, I got another. Because I have two templates created for the posts - and somehow I can not choose which template I want to use when I create a new post in wordpress - I want to delete one of them. How can I accomplish that?

In short:
I was wondering how I can delete a template in my created childtheme.

Thanks in advance!
Joëlle