In general, complimentary items should indeed be returned if you are returning your entire order.
However, each brand has a different policy on this matter.
So, to be sure:
📩 We invite you to contact directly the brand from which you made your purchase (by visiting their website), to obtain the exact answer.
❌ The Elyn chat (bottom right) is only dedicated to technical issues related to the return interface: we do not handle additional requests.