I am a seller on Lazada.

Yes, you can return it as long as it's within the return period.

Btw, usually the return package would be in used condition, be it from the marking being tear open or being throw around during transportation back and forth and we won't be able to resell the parcel to another buyer again.

It will proceed, you will still get back your money. Just that the seller would ended up with a used item that they can't resell to another buyer again.

If I'm the seller, I would prefer the buyer to text me sharing me the place where you got a better deal and I'll match the price different, than you cancelling the order.