I had trouble figuring this out, so here goes. To completely wipe your blackberry clean varies by device. But it can be done. I had a 7100 series and the steps are:
- Settings (looks like a folder with gears on the top right)
- Options (just has two gears)
- Security Options – select this from the visible menu by scrolling down
- General Settings – select this from the visible menu by scrolling down
- << Press Scroll Wheel in >> – this shows a scroll wheel menu
- On the resulting scroll wheel menu there is an option to "wipe handheld" – That is what you want.
I mention this because several places on the interwebs told me to go to options and select "wipe handheld" but of course this ONLY shows up for this particular device in a scroll wheel menu.