If you moved the PowerStore into the root of your site you should be able to access it with a URL to your site like this:
index.php
If you have index files specified as the default document then there is no need to add that part to the URL. If you have your store in a directory inside of your site root, like in a folder called store for example then you would access it like this:
store/
The URL to the store is the same as your admin, just minus the admin part in the URL.