I think it will be well to distinguish between (a) qualitative experience, (b) qualia, and (c) the given.
I doubt that anyone denies qualitative experience. Sellars, anyway, did not. It seems to be a pre- philosophical fact, not a matter of controversy. In “Philosophy and the Scientific Image of Man” (PSIM) Sellars contrasts the scientific world image with the "manifest" world image, which includes qualitative experience. Sellars's emphasis in that work is to reconcile the two "world images", to give a place to each, within a single "synoptic" world image.
'Qualia' is a metaphysical term. Qualitative experience is explained by positing non- physical entities: the qualia. Sellars does not acknowledge qualia. In both Empiricism and the Philosophy of Mind (EPM) and PSIM Sellars puts it by arguing that only science, not sense experience, is sovereign to decide what exists and what does not exist. And since present science is materialistic, there is no place for non- material entities like qualia. Here is how Sellars formulates that principle in EPM, paraphrasing Protagoras:
In the dimension of describing and explaining the world, science is the measure of all things, of what is that it is, and of what is not that it is not. (EPM §41)
'The given' is an epistemological term. It refers to a perceptual judgement which is certain, indubitable, by its very act. Sellars argues at length against the given in EPM. He suggests there that the very idea of the given is incoherent, because every judgement is a choice between alternatives. An indubitable judgement is therefore a contradiction in terms. So, while Sellars does not deny qualitative experience, he does deny that the basic perceptual judgments, the bases of empirical knowledge, are judgments about "given" qualitative experience. In fact, because of his principle that scientific theory, not perception, determines existence, Sellars denies the very fact of perceptual judgments, because judgments imply ontological commitments. He posits instead perceptual reports. Perceptual reports, a la Sellars, are like judgments in being fallible, yet are unlike judgments in not carrying with them ontological commitments.