Please help me format my internal SD card

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http://androidforums.com – Please help me format my internal SD card. Right now it looks like this, and I want to format it to default folders without risks. For example, I did a secure backup a really long time ago, and I wish to erase the folder it created with it, but at the same time know if it's safe to delete, or have a way to delete everything, and only leave default stock folders. I have ClockWorkMod Recovery v6.0.1.1, and I see the option "mounts and storage" / "format /sdcard", but I don't know if that's the right option. Could somebody guide me please? (General)