Removing a Disabled Task requires calling Stop first.

[lynxbat]

❯ build/bin/snapctl task list
ID                   NAME                        STATE       HIT     MISS    FAIL    CREATED         LAST FAILURE
0c9ad69d-f8a2-409c-b162-de6f3e3bd4d5     Task-0c9ad69d-f8a2-409c-b162-de6f3e3bd4d5   Disabled    10      0   10      2:16PM 6-30-2016    Publish call error: Post http://127.0.0.1:8086/write<snip>

❯ build/bin/snapctl task remove 0c9ad69d-f8a2-409c-b162-de6f3e3bd4d5                                                                       ✭
Error stopping task:
Task must be stopped

Ideally a Disabled Task should be something that can be removed without having to stop.