Boot your 3DS holding... if I remember right... L+R+Up+A and press the Cancel button. This will remove the nag. From there, use tubehax DNS to block updates
From what it says, it seems it can't delete system updates, so you'll have to remove them manually by doing what the reply above mine says. Thread also mentions blocking Ninty's system update server on the router instead of using Tubehax's DNS.
I'm pretty sure they meant httpwn, which allows for online play and no systemp updates on 10.7. don't worry m8, gotta link right here. http://gbatemp.net/index.php?threads/420224/
Rumiko Takahashi got so much fan email about the character that she brought her back in the manga, it was going to be completely different originally (with the alien of the week type).