Sort:  

One easy way to return SBD is to use Promote. When you Promote a post, the SBD used goes directly into the reward pool. It is effectively burning the payment.

AFAIK we can just transfer anything to @null.

Yeah, that's how promotion works. If you transfer to @null with a permlink, it will put you in the promoted list. If you use the promote button, you should notice a transfer to @null after as well. It's all basically the same thing.

You can still transfer without linking, right? But yeah I understand now what you mean.

Yup. You could always do that. I guess that would be a FOR REAL burn because you're definitely not getting anything out of it. LOL

So if you want to burn SBD, one way is to just create a post and promote it with whatever amount you want to burn.

Good question, I am not aware of an account that can be used for that - but it would be a good idea to have one.