You mean the death of the false ego to leave room to the real ego/higher self/godself? I thought Satanism is more dedicated to increase the ego rather than destroy it.
I know this post is a little old, but I'm rather tired of being accused of this line of thought for being a Satanist.
The Fraternitas Saturni, arguably the oldest Satanic organization, had a lot more in common with Thelema. Ego loss was still a stage of their ritual advancement, since it was based on alchemy. You could say that this was to make room for the "Higher Self," but it's not too much different from finding your individual True Will and devoting yourself to its fulfillment.
Ironically, I think to seek to "increase the ego" in any form is ironically more self-destructive than anything else. It's sort of unambiguously bad for the individual, whether you're adhering to master or slave moralities. Even LaVey knew this and warned about it, specifically calling out excessive indulgence and a lack of self-awareness as hurdles to avoid. Ultimately, that decries the ego, which shouldn't be all that surprising since LaVey was also heavily influenced by Thelema.
There's some confusion here, because Satanism tends to align with ethical egoism and generally be fairly egocentric, but the "ego" in these concepts is entirely different from the "ego" in ego death. Ego death is actually more closely associated with Jung's concept of "individuation," which sounds a lot more like the language you would expect to find in a discussion on Satanism but they're essentially the same process.
Ego death itself is a transient experience used for insight. It's not a virtue to strive for or an end-goal or anything; it's an altered state of consciousness. Mystic practices like Zen or jnanamarga emphasize the temporal nature of these experiences while emphasizing the importance of applying the insight gained from them to daily life; they don't seek to destroy the Self.
ETA: Now, in those practices, ego death is meant to be a stepping stone to some pretty un-Satanic (imo) lines of thought like selflessness and altruism, so I understand why that's often the connotation. Technically, though, that's just Buddhism and Hinduism, not ego death. As a state of mind, it can be used for other things.