You can install Webmin and do it from there. You tend to still have garbage left even with Webmin. I would personally save your files from your Home folder and then put a new image on the SD card.
Ren: Now listen, Cadet. I've got a job for you. See this button? Ren: Don't touch it! It's the History Eraser button, you fool! Stimpy: So what'll happen? Ren: That's just it. We don't know. Maybe something bad, maybe something good.