This really depends on which theme you’re using. Some themes will have an option to remove these items (try widgets or theme options), while others you’ll have to adjust manually in the theme files.
If you’re looking to develop a more static website instead of a blog it might be helpful to look to purchase a theme from somewhere like WooThemes (https://www.woothemes.com/) or ThemeForest (https://themeforest.net/).
If you don’t want to spend any money you can find a ton of free themes at https://www.ads-software.com/extend/themes/.
I hope that’s helpful. Good luck.
