Can I move an item to a different source

I copied a class from the PHB to use as a baseline for creating a new one.

The copied class shows in the PHB source. I want to change the source, is there a way to do that?

In the "Classes" campaign data list open the group list at the top by clicking on the down arrow - this displays the currently available groups. You can add a new group if you like. Drag/drop your class to the group you want it to be a part of.

That worked, Thank You