The ornamental design for a handle for mounting and dismounting riding lawnmower, as shown and described.
FIG. 1 is an isometric front view of a handle for mounting and dismounting riding lawnmower showing my new design.
FIG. 2 is and isometric rear view thereof.
FIG. 3 is a front view thereof.
FIG. 4 is a side view thereof; and,
FIG. 5 is a front perspective view thereof shown mounted to a riding lawnmower in use condition.
The broken line showing of a riding lawnmower in FIG. 5 is included for the purpose of illustrating environmental subject matter only and forms no part of the claimed design.