Delete spawners via mob

I've this idea to set up dungeons around a custom map, each with their own boss. The plan is that once the boss is defeated it removes all spawners in the dungeon. To do so i tried using:

Skills:
- command{c="mm spawners delete blah"} ~onDeath

But i'm being told this command cannot be issued from the console. Anyone know why or know of a solution to this? I'd rather not abandon this idea