Below, you will see that your Themes library can be simple, and not filled with 10 themes like most blogs. Lowering the amount of Themes in your blog can help your site load faster. So I, myself, decided to delete all the ones I probably wouldn’t be using for the next few years. I made it so that the main theme was there, in this case I am using Newspaper X, and the other theme installed is a default theme that comes with WordPress. Check out books on Walmart and Amazon on how to do tasks like this.
It’s important to have a WordPress theme that came with WordPress, incase you need to trouble shoot anything. You can of course disable plugins if there are any problems with WordPress, but the next step is disabling themes and activating your blog on a theme that is not normally used with your blog. Then you can check to see if the theme itself is causing what ever problem with your blog that might be having problems. Anyways, I hope that helps you and hope your site loads faster after deleting some themes.
Incase you might be wondering, you simply click on the theme you want to delete, then you click on Delete (you will see an option in your web browser when you click on the them). Hope that helps, make sure you Like and Subscribe, Share, and yeah, that’s it :).