In order to hard reset a Nokia Lumia 630, you should perform the following steps.
Remember! Hard reset will delete all the data on your device; pictures, contacts, messages, apps and more.
Nokia Lumia 630 device will be brought back to the default configuration of a brand new device.
1. Press and hold the Power button until the phone turns off.
2. Now press and hold the Volume Down + Power buttons. Let go of them when the phone vibrates.
3. Press (yep, all that pressing...) those buttons in exacly this sequence: Volume Up > Volume Down > Power button > Volume Down
4. Phone will now reset and restart. Give it time to do it.