The ornamental design for a pillow having a removableneck support, as shown and described.
FIG. 1 is a top perspective view of a pillow having a removable neck support with the neck support inserted;
FIG. 2 is a top perspective view of the pillow having a removable neck support with the neck support removed;
FIG. 3 is a top view of the having a removable neck support with the neck support inserted;
FIG. 4 is a front view of the pillow having a removable neck support with the neck support inserted;
FIG. 5 is a bottom view of the pillow having a removable neck support with the neck support inserted;
FIG. 6 is a back view of the pillow having a removable neck support with the neck support inserted; and,
FIG. 7 is a left side view of the pillow having a removable neck support with the neck support inserted.
Right side views not shown are mirror images of left side views. In the drawings, the broken lines illustrate environment and form no part of the claimed design.