A free app for Android, by Giuseppe Romano.
Secure Eraser is a data eraser app that is based on the concept of an integrated shredder. Secure Eraser allows you to permanently erase data from your internal storage and even from external memory cards, like memory sticks and SD cards.
Secure Eraser has been integrated into the operating system of the phone. There is no need to install a separate application. It works as an add-on to the standard operating system of the phone. It has been tested on various Android devices, including tablets and smartphones.
The app permanently erases all the data from the device and makes it impossible for anyone to restore data from the device. The data is erased from the device's memory and is not just removed from the device, but is also destroyed.