How to force a factory reset or hard reset on Elephone devices

Elephone C1X Elephone C1X
Elephone Z1 Elephone Z1
Elephone C1Max Elephone C1Max
Elephone C1 Mini Elephone C1 Mini
Elephone A1 Elephone A1
Elephone P8 (2017) Elephone P8 (2017)
Elephone P8 Mini Elephone P8 Mini
Elephone A8 Elephone A8
Elephone S8 Elephone S8
Elephone H1 Elephone H1
Elephone P8 3D Elephone P8 3D
Elephone P8 Max Elephone P8 Max
Elephone U Elephone U
Elephone U Pro Elephone U Pro
Elephone A4 Elephone A4
Elephone Soldier Elephone Soldier
Elephone A4 Pro Elephone A4 Pro
Elephone A2 Elephone A2
Elephone A2 Pro Elephone A2 Pro
Elephone P11 Elephone P11