Installation Directory Is Not Empty Please Install To An Empty Location

Installing your preferred platform for your website is made easier using the application installers of your cPanel; however, there may be a time when you encounter an error while installing an application similar to the images below. For this example, we will use WordPress.
This error presents when there are files already present in the directory you're trying to install WordPress to and can be remedied by clearing the directory. This article covers how to achieve this for your primary domain, addon, and subdomains.

rmdir not empty
rm -rf dir-name

directory is not empty Windows
// On windows
C:>rmdir /S nonemptydir

Remove directory is not empty Windows
rd /s /q "path"

QuickInstall

QuickInstall is another application you will find in cPanel. Since this application is available to few users only, you can still utilize the QuickInstall as your installer though we strongly suggest using Softaculous. Please refer to this article for detailed instructions on how to use this application, QuickInstall.
When you're trying to install WordPress with the QuickInstall method, sometimes you'll get the error "Installation directory is not empty. Please install to an empty location".

To resolve the QuickInstall installation directory issue, please follow the steps below.

In the cPanel, navigate to the File Manager under the Files section.
Inside the File Manager, locate the domain's document root or directory.

For Primary Domain:
Click the folder public_html.

For Addon or Subdomains:
Click the addon or subdomain's document root or directory. To make sure you're in the correct document root, go to cPanel's Domains section, then select Addon Domains or Subdomains.

Locate your domain, then click on the document root link beside it.

In the upper right-hand corner, click on the Settings button.
Check the box next to Show Hidden Files and click Save. This allows you to see all of the files in the folder.
Select all of the files and folders in the directory by clicking the Select All button at the top of the window.
Then, click x Delete to move everything to the trash.

Reference Blog

Installation Directory Is Not Empty Please Install To An Empty Location