Hi
As far as GST is concerned, if you have not claimed the relevant ITC, you need not file anything in GST returns when you are returning the goods.
Debit notes/ credit notes in GST are in relation to outward supplies and shall be issued by your supplier. In your case, the supplier shall issue a credit note.
For accounting purposes and not considering GST, you may raise a general debit note when you are returning the goods.
If you had claimed the ITC in relation to such supplies, you may reverse the same now.