Your situation is somewhat common. One installs WordPress into their root, and then wonders about how to install other products.
For me, I like to keep applications separate. I would install WordPress into ..root/WordPress, Moodle into ..root/moodle, joomla into ..root/joomla, etc. This makes updating each application easier, and helps you keep your web server organized. It also will help when it comes time to update applications.
Well, you didn't do it this way (probably because you did not anticipate the need for moodle, or didn't think ahead.) I suggest that you ask your hosting company how to move the install of your WordPress into its own folder. Your "homepage" can be created that gives your customers the ability to choose any of your products.
There are many ways to have both applications installed. My comments are only suggestions.