Huh? No, they didn't. At this point, no one has any idea how she factors into the story since she was so closely connected to K9999...who has since been erased altogether, and replaced with Nameless, who in turn is nothing like him beyond a shared moveset and being the 9,999th Kyo clone (doesn't look like him, doesn't act like him, doesn't have the same VA, doesn't have the same motivations, etc.). Comparatively, Angel has absolutely nothing to do with Nameless story-wise. She's not dead in the series so much as in limbo.This.
It's so lame they killed her off
This was never true. Eolith developed 2001 and 2002, yes, but they never owned the rights to any specific characters, Angel, May Lee, and K9999 included.King of Fighters: KoF's roster has always been pretty variable, but the new sprites have kinda killed it since there's so few characters nowadays, especially on the female side, even though KoF has a really diverse cast. And now SNK's starting from scratch again and switching to a SF4/GGXrd style of cel-shaded 3D models. Hopefully it'll work out better in the long run as the HD sprites just weren't economical in terms of how long it took them to make each character. I'd love to see Vanessa, Whip, and some others back. I wouldn't hold my breath on Angel, though - any characters introduced in KoF 2001, such as her and May Lee, are owned by Eolith (the South Korean company that developed that and 2002), not SNK.