Are subgenres not deletable from keyword lists?

Just finished (I thought) auditing the keywords for the anime series "Ai shite naito" (1983), submitting deletions for 18 keywords incorrectly repeated for each episode, even though they already exist at the series level. All were processed EXCEPT ONE: “subgenre: hand drawn animation. Are subgenres not deletable from keyword lists? Can you delete this incorrect keyword from the 42 episodes? (I resubmitted one as a test, and it was also not accepted.)