First, click Collaborators on the top left side of your SideDrawer
Next, choose the SideDrawer that you'd like to make the changes to. In this example, Jesse wants to change the relationship for Rob Rosenblatt.
To change the relationship from Personal to Professional, simply click the relationship line on the left and make the correct change in the pop up menu.
To further choose the type of business or personal relationship, click the relationship line on the right and make the correct change in the pop up menu.