How to unbind skin layer in Maya18??


Hi there. Maya newbie.
Trying out a few different things to learn.
Id like to modify a pre made character, just the face.
How do I sculpt on this to change the features?
Autodesk help is awful, for everything and cant find any decent videos for this.
Under how to detach skin the answer is “Skin- Detch Skin” which is basically telling me you detach the skin by detaching it which is totally useless lol.
This is the error message etc…

ally useless to me.