I like using two pliers, just about any flavour of pliers, one each to grip the insulated conductors on either side of the ground wire at the end of the cable. Twist the pliers in opposite directions. . .this starts a tear in the sheath 1/2" to 1" long and exposes the ground wire. Release one plier and reposition it to firmly grip the ground wire. Pull the two pliers apart. . .the ground wire acts like a zipper in the sheath, tearing through it. . .stop when enough length is exposed.
Set one plier aside. Most of the time, the sheath left around the insulated conductors will fold back just with finger pressure, exposing a short end of insulated conductor that can be gripped with the plier and pulled out.
Use a knife or side cutters to trim the sheath. Cut off the 1" of plier damaged conductor.
