In Stack Exchange jargon, burninating a tag means removing it from the history of questions. It is done from Stack Exchange staff, and its effect is making it vanish from a question, as it has never been used. It is different from editing it out, as in that case there would be created a revision, and the tag could be re-added by reverting the revision removing it.
It is also different from black-listing a tag, which is avoiding a tag can be entered, even from moderators. Black-listing is doing when none of the question is using the black-listed tag; that can be done by manually editing the questions using it, or burninating the tag before black-listing it.
As burninating is done from Stack Exchange staff, it is normally required when a tag that is not helpful is kept to be used, and there is no way to remove it from new questions because the number of new questions using it is higher than the number of questions from which the tag is removed. This means that burninating a tag is not done when the number of questions using it is very limited, and there are no new questions using it. In such case, editing the tag from the question is what should be done.