It’s a good practice to remove unused themes so that you don’t have to maintain them with updates for security purposes.
If a theme is installed on your site, it means all the files still exist on your server. That means the code could still be exploited, even if the theme isn’t active. So you either have to maintain the updates for the theme, or you should just remove it.
Accessibility is something that I’m really into… in theory. I believe everyone should have full access to the internet no matter what challenges they face or if they are using different devices to navigate and access the web.
But in reality I have not put as much work into this as I need to. So when I received the pitch email about the Accessibility Checker plugin, I thought it was a good opportunity to figure out just how badly I’m sucking at this, and find a starting point to try to address some of the issues.