Why can't I completely uninstall a theme from my online store?

[Byartpolecuff]

Hello Shopify Team.
We are in the process of reorganizing our store.
We reviewed some of the themes we received. And we felt some glitches in these themes. When we want to remove our theme, it comes back again. When installing the Simple theme, it contains the data of the EcomSolid - DO NOT DELETE theme. We want to completely remove EcomSolid - DO NOT DELETE theme. We want to reinstall Simple theme, please help with this.