There is no specific requirement on the type of packaging. You can use a delivery box or any other form of secure packaging as long as it adheres to the maximum parcel dimensions.
However, kindly ensure that any irrelevant or old shipping information / addresses are crossed out or removed (i.e. if you are using an old packaging box). This is to avoid confusing our logistics partners.
The key here is to ensure that your return item is securely packaged and will not be separated from the package / cover during transit.