You probably have a few hosting packaged on your server that you connect to PowerPanel. If you connect your server to PowerPanel these packaged will be retrieved from your server. You can read how to add your server to PowerPanel on the following support item:
If you have succesfully connected the server to PowerPanel you can find the sites current on the server back in the site conflicts.
Go to Hosting -> Site conflits to view all your sites. Here you will have to connect these sites to a customer so that the customer can manage his site himself.
To resolve a site conflict, click on it and search the customer, after that you can select the right hostingplan and the subscription date. Click on round up and you are done.