What is the ruling if a player picks up their ball without holing out on the green?

The correct ruling for a player who picks up their ball without holing out is that the player incurs a penalty stroke. According to the rules of golf, a player must complete the hole by holing out their ball. If a player prematurely picks up their ball without finishing the hole, they are not only affecting their score but also potentially disrupting the integrity of the game. The appropriate consequence for this action is to apply a penalty stroke, which emphasizes the importance of completing the course of play according to the established rules.

The other options do not align with the rules governing this situation. A warning may not adequately address the severity of the action, and a disqualification would be excessive for this specific infringement unless it is combined with other forms of misconduct. Similarly, requiring the player to putt again from the same spot does not apply since the rules regarding improperly lifting a ball specifically dictate that a penalty stroke is incurred instead.