Move Deleter won't remove Surf...

[The Songbird]

I took my Zigzagoon to the Move Deleter to remove its HM moves. It had Surf, Rock Smash, Cut, and Tackle. The Move Deter removed Rock Smash and Cut no problem, but when I tried to get Surf removed, he said this: "Hm! Your Zigzagoon doesn't seem willing to forget Surf." Is there any way to change it?

[Twinx]

It's because no other pokemon of yours knows Surf.
Teach Surf to another slave pokemon, and then Zigzagoon will be able to forget Surf.

[SteSean]

It's just to make sure that you won't forget to teach Surf to another Pokemon, I guess.