1- Click the Products / Services button from the menu after logging in to FieldPie.
2- Click the product you want to edit its product group.
3- Click the Edit Product Groups 
button at the right side of the 'Product Group' area.
4- You can either add a new product group or delete current product group from the 'Edit Product Group' pop-up.
5- You can edit the product groups by clicking the SAVE button.