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

Archos Oxygen 63 Archos Oxygen 63
Archos Oxygen 57 Archos Oxygen 57
Archos Oxygen 68XL Archos Oxygen 68XL
Archos Saphir 50X Archos Saphir 50X
Archos Diamond Omega Archos Diamond Omega
Archos Diamond Alpha + Archos Diamond Alpha +
Archos Diamond Tab Archos Diamond Tab
Archos Diamond Alpha Archos Diamond Alpha
Archos Sense 55s Archos Sense 55s
Archos Diamond Gamma Archos Diamond Gamma
Archos Sense 50x Archos Sense 50x
Archos 40 Titanium Archos 40 Titanium
Archos 45 Titanium Archos 45 Titanium
Archos 50 Titanium Archos 50 Titanium
Archos 53 Titanium Archos 53 Titanium
Archos 45 Platinum Archos 45 Platinum
Archos 50 Platinum Archos 50 Platinum
Archos 53 Platinum Archos 53 Platinum
Archos 50 Oxygen Archos 50 Oxygen
Archos 45 Helium 4G Archos 45 Helium 4G