Most of people worry about their private data would be revealed and stealed by other unknown people if they sell their Android for getting a new one.
Therefore, they choose to factory reset for detele all the data from Android phone . but i don't think it is a good idea to erase Andorid data
To permanently delete Android data ,you can use a Erasephone,which can permanently delete somthing from Android phone,
Erasephone can be used to remove messages,photos,videos,contacts,and other files ,
Please read this use guide about How to Erase Android Data Permanently,
So no one can get you personal information and data from Android,after you sell, donate or give it away.
It is really necessary to delete everything on your Android , because you will never know who will get your Android and what he will do with your private data. Since restoring the device to factory settings is useless,
why not use professional Android data erasing software like Erasephont.
Step 1: Link Android to Computer and Launch the Program
Firstly, you need download, install the Windows/Mac version and open this program on computer. Then connect your Android device to PC via a USB cable.
Step 2. Select the right Security Level and Begin to Erase Data
Choose security levels according to your need. Then press the "Start" option, the program will start to clear your Android device immediately.
You can use this eraser tool, there are some Android data eraser software in the market, but few can be completely and permanently delete the data on Android,
even if data has been cleared, some professional Android data recovery software can recover them later.
Read more: Delete and clean Android phone