Adjust the layout of your disk(s) here. You can remove or create partitions, change the filesystem of a partition or change its size and even view what is in them before you start.
There is a tab for every detected hard disk or other storage device, like an USB key. For example sda, sdb and sdc if there are three of them.
Push to wipe all partitions on the selected storage device
For all other actions: click on the desired partition first. Then view it, or choose a filesystem and a mount point, resize it or wipe it.