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

Icemobile Prime 3.5 Icemobile Prime 3.5
Icemobile Prime 5.5 Icemobile Prime 5.5
Icemobile Gravity 4.0 Icemobile Gravity 4.0
Icemobile Prime 4.0 Plus Icemobile Prime 4.0 Plus
Icemobile Prime 5.0 Icemobile Prime 5.0
Icemobile Prime 5.0 Plus Icemobile Prime 5.0 Plus
Icemobile G8 Icemobile G8