The ornamental design for an accessory golftowel, as shown and described.
FIG. 1 is a top, right side perspective view of an accessory golf towel showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a bottom end view thereof;
FIG. 4 is a left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a rear view thereof; and,
FIG. 7 is a top end view thereof, the broken lines depict stitching and a divot tool for illustrative purposes only and form no part of the claimed design.