No, if an object is moving upward with a constant velocity, you would not neglect the gravitational force and set it as zero. The gravitational force would still be acting on the object, even if it is moving with a constant velocity.
When an object is moving with a constant velocity, it means that the net force acting on the object is zero. In the case of upward motion against gravity, the gravitational force pulling the object downward is balanced by an equal and opposite force exerted by another agent (such as an applied force or an opposing force from air resistance). This balancing of forces results in a constant velocity.
In this scenario, the gravitational force is not neglected but is rather canceled out by another force to maintain the constant velocity. So, the gravitational force is still present, but its effect is counteracted by other forces, resulting in no net acceleration and a constant velocity.