The first stage was to remove all the bits I didn't need or that would get in the way whilst I worked. This included the lenses, the internal foam, the grill work, tusks and all the ruddy Velcro. I wanted to remove the straps too but couldn't find anything to replace them with so I reluctantly left them in place.
After half an hour or so, the inside of the mask looked like this. All the parts that I had removed were carefully packed up for possible future use. I next gave the thing a wash down with soapy water and left it to dry.