Hidden PP child theme images & Site speed !?

There’s no option for DP in v7 forum topic. The issue is that DP v 7 come with 1800-1900 hidden images contained in PPT file and related to over 20+ child themes. Once it is decided what child theme is used is it safe to delete all other child themes that come included with PP, which just sit on my server, unused. I was shocked how many images (every dot & arrow) existed outside the thumb folder. It took forever to optimize. But I rather have them out. Thanks.