I vote no don't kill her . There are ways that Teela could become a Sorceress without killing her mother . I think they should have her over hear the truth & then she could confront MAA & the Sorceress . After that they could all make up & begin her training & her connecting with her mother but before she is really trained much I think they should have someone kidnap the Sorceress . That way Teela is forced to use her powers plus it could make a great storyline He-Man & The Masters of the Universe : The search for the Sorceress .
I remember someone madeup an evil Sorceress maybe she could challenge Teela . Fisto could also go MIA around that time & Pravus ( I hope that how it's spelled) could return