How to Format/wipe all Android Phone

If you are frustrated when it takes 10 minutes to run an app; you mistakenly tamper with a setting or something you ought not to do and not able to revert it back, or some consistent bugs you find difficult to remove. It may be time for a factory reset. Factory reset will erase all the current data stored in the device and restore all the settings back to the original ones.
Guide to Format an Android Phone
Part 1. Format Android Device with Factory Reset

Part 2. Format Android in Recovery Mode
Note: Before formatting an Android phone like Samsung Galaxy S6, LG G3, Sony Xperia Z3, HTC One M8, Google Nexus 6, etc. you should
back up the Android data to computer in advance.
Part 1. Format Android Device with Factory Reset
Click into the Settings menu. Then, tap “Backup and reset ” option under the “PERSONALIZATION” panel. Choose “Factory data reset ” from the options. A note will warn you that all data will be thoroughly erased from device memory. Tap “Reset device” button at the bottom of the screen to confirm formatting.

Part 2. Format Android in Recovery Mode

To enter Recovery Mode, you should firstly switch Android smartphone off. Then, press and hold the Power key, Volume up and Home button at the same time, you will get into the Recovery Mode interface as below. Scroll down to select wipe data/factory reset option with the Volume down button and use Power key to confirm it.