So Check out how to accomplish hard reset by hardware keys and through android settings. As a result your SAMSUNG Galaxy A9 will be as new and your core will run faster.
1. Restart your Samsung Galaxyby pressing the Power button .
2. Immediately press and holdpower + Volume Up + Bixbybuttons before the device reboots.
3. Release all keys when Samsung Galaxy logo appears.The “Installing system update” and “No command” screens will appear, followed by the Android Recovery menu.
4. Using the volume down button scroll to the option “wipe data/factory reset” and select it using the power button.
5. You will be brought to a screen as the one shown below. Using the volume down button scroll to the option “yes” and use the power button to select it.Wait for the reset to be complete.
6. Select reboot system now using the power button and wait for the device to restart .
7. This normally takes upto 10 minutes.Congratulations you have successfully hard reset your Samsung Galaxy A9.