I claim the ornamental design for a set of grout removal bits, as shown and described.
FIG. 1 is a front view of a set of grout removal bits.
FIG. 2 is a rear view of the claimed design.
FIG. 3 is a left side view of the claimed design.
FIG. 4 is a right side view of the claimed design.
FIG. 5 is a top view of the claimed design.
FIG. 6 is a bottom view of the claimed design; and,
FIG. 7 is an isometric view of the claimed design wherein a first bit is attached to a removable handle that is depicted in dashed lines and forms no part of the claimed design.