There aren't many 9' snakes that have fangs except king cobras.
If you want to hang it on the wall or use it on a bow you can cut the head off.
If you want to leave the head on the skin for the wall or taxidermy,it has to be skinned completely out to the lips.It can cling tight to the skull on top of the head and from the eyes forward.It is just a matter of skinning it free from the bone with a small,sharp knife or scalpel.
Many North American snakes,you can easily pull the skin off the carcass but the tail needs to be skinned carefully-that area from vent to tail tip.
I suspect yours may be a boa or python and if so,there skin clings much tighter to the carcass and you may have to use knife work the full length to get it free.Fleshing would be more work also.
A lot of NA snakes could be fleshed with a spoon or dull knife but I don't think you could get away with that on a boa or python.