Can't the lower radiator hose to drain the coolant (Peugeot 308 BlueHDI)

I can't remove the lower radiator hose from my 308 BlueHDI to drain the coolant. Does anyone have a tip for doing this? I've removed the cap from the reservoir in case of a vacuum effect, and the metal clamp around the fitting. But nothing works, the fitting won't disconnect, and I'm afraid of breaking it by forcing it too much. To be honest, I'm not sure where the separation between the two fittings is located.

https://preview.redd.it/ajyocrx5tthf1.png?width=1280&format=png&auto=webp&s=804f68cf910ecdd0d8c41c272267eefef4fc0ed1