Log in your cPanel account -> Sofware -> Site Software -> WordPress -> select a domain name -> Uninstall:
When WordPres will be uninstalled you need to delete some files manually. If you added domain as Addon go to Domains -> Addon Domains -> look at the path where you need to go to delete these files.
So, according to this screenshot we need to go to File Manager -> Public html -> domain name and delete all files that are remained after WordPress is uninstalled. The same with subdomains.
If you want to uninstall WordPress on your primary domain you need to delete all files except of ‘cgi-bin’ (or other) folder.
After that Go to Sofware -> Site Software and click ‘WordPress’:
Here you can choose your Installation URL (to install directly into a domain’s document root, leave the installation URL’s path blank), type in your admin username, create or generate password and add your email address. To edit your website title, please fill in Blog name and Blog description fields. To finish the installation process, click Install. At the bottom of the page there is an option of uninstalling CMS WP available as well.
After the installation is complete, you will receive your WP login credentials.
If you want to install WordPress on your cPanel manually, download WP file from https://wordpress.org and follow further instructions provided by your hosting provider.