Clio 3 K4M Coolant Air Bleeder Valve

[RumMaple]

Hi Folks

My first and probably not my last post on this forum.

My Clio 3 K4M 1'6L 2007 model recently overheated and I was able to make it to the closest garage, I slowly removed the coolant cap and lots of boiling water and coolant gushed out, I started the engine and filled the coolant reservoir with cold water until all the air escaped and the temp dropped low enough for me to amble home.

I intend draining the radiator tomorrow and filling up with new coolant however there is a bleed valve close to the thermostat I believe that I need to loosen to bleed any air in the system, I am not sure what tool I need to use to loosen the bleed valve and don't want to damage it by using force etc.

Can anyone advise how I go about loosening the bleed valve please.

Much appreciated.