XF 2.0 Minifying JavaScript files and deleting old junk product

[Nerbert]

I'm working on a testing addon to learn how things work and I'm having trouble minifying my JS. I have a build,json file in Nerbert/Testing like this

{

    "additional_files": [
        "js/vendor/nerbert"
    ],
    "minify": [
        "js/vendor/nerbert/testing1.js"
    ]
}

My file is Nerbert/Testing/_files/js/vendor/nerbert/testing1.js

I ran the build command to minify the file but no minified version appears in _files/js/vendor/nerbert/ or in js/vendor/nerbert/.

Does the minification only happen when the product is installed? Is there any way to do this before release?

I have a second question: This is my second attempt on this product so I uninstalled the first version but now it shows as ready to install. I want to completely delete it. How do I do that?