Problem with NPC respawning (ascent)

[Apollo54]

I'm really new with running ascent. I spawned Onyxia in IF with the .npc spawn <ID>
I tried .kill but she respawns. I tried .npc return and tried to restart the server but she keeps respawning. Anyone know the command so she won't respawn in IF after killed?

Thanks for the help.

[MentaL]

[KingXCrosses]

.npc del
(.npc delete)