Ranking WordPress Site, but going HTML? Will I lose my rank?

Hey BHW,

I'm currently ranking strongly for my money site that's wordpress. However, I have found a killer theme for my site, except it's HTML…

Now, I use yoast SEO, post a high end blog post around once a week, and rank for multiple keywords in my niche (top 3).

I am wondering if changing my theme to HTML from wordpress will affect my ranking. Will changing my theme affect SEO?

Any advice is appreciated.