Erase completely or format storage

[Marios Georgiou]

I need a tool that will erase entire internal storage and sd card but preferably format em if such
an app exist.

 

[psionandy]

Make sure they are encrypted.. then factory reset.

The factory reset throws away the encryption keys... so if anyone was able to recover anything, all they would get would be random encrypted fragments with no way of converting them into meaningful data.

 

[svim]

The tools you need are already integral to the Android operating system. Remove your Google account and any other services you have set up in the Settings >> Accounts menu, confirm your internal storage is encrypted in the Settings >> Security menu, and then do a Factory Reset.

At that stage, because you removed the account authentication(s) whenever you start up that phone it's going to need to go through the same set up process as when you first go it; and with the internal storage being encrypted (which it probably already was enabled) and the Reset wiping the data partition, even if someone were to attempt to use some kind of restore/retrieve utility because of the encryption it would only be able to see bits of randomized data.
And don't forget to remove any SIM or microSD cards.