Hacking Help removing FC and NNID

[CH0LO]

So i'm selling my 3DS and i need to take everything off of it (except cfw)
i have removed my NNID but i need to remove my Friend code and the mii's

How can i do this?

p.s if there's anything else i should remove please let me know!

 

[DocKlokMan]

Just system format it from the System app if you need to remove everything but CFW. Formatting doesn't affect CFW.