Wipe your 3ds's or 2ds''s sd card

You need these things: You can do it using two methods.
 * A computer
 * An SD Card (Micro SD in case you have a New 3DS)

1. The n00b method, A.K.A. Delete everything!

 * 1) Mount your SD card on your computer
 * 2) Open the root folder
 * 3) CTRL + A -> Del

2. The pr0 method, A.K.A. format a:
And now you're good to go, with your empty SD Card! Remember, both of these methods WILL delete everything from that poor memory card. At least light a candle in memory of it!
 * 1) Mount your SD card on your computer
 * 2) Open 'My Computer'
 * 3) Right Click on your SD Card -> Format -> OK