How do I factory reset a locked Android phone
When you are locked out of your Android smartphone and cannot do anything with it, and you cannot unlock the screen with either a password or PIN, the only option to recover the phone is to factory reset it from outside.
What to do with locked phone
As the smartphones are now using security features like password, pin codes, or visual checks to unlock the phone, it can become easily possible to get locked out of your own phone, after having forgotten the access sequence, without any possibility to get the access to the phone back.
In order to get back to the phone, the only and last solution is to factory reset the Android phone, unless it can be unlocked from the Google device manager.
Google device manager
Before doing a factory reset, try to access the device in the Android device manager.
It might be the case, depending on the Android phone, that Android device manager is able to unlock the phone, providing that you succeed at the security verification.
Hard reset Android phone
When the phone is locked out, the last solution is to perform a hard reset.
Start by turning off the phone, by long pressing the power button even when phone is locked, and selecting the power off option.
Then, hold the power button and the volume down button simultaneously for up to 20 seconds, until the boot menu of the phone shows up.
Factory reset phone from boot menu
Once in the boot menu, there will be an option to factory reset the phone, accessible directly from there.
To navigate in the boot menu, use the volume buttons to go up or down on the option selection, and use the power button to apply the selection.
Take care, once the phone has been factory reseted, all data will be lost!