If a person wants to commit suicide and you can prevent them from doing so, will you?
Like grabbing their arm and pulling them off the ledge? Yes, it would be automatic.
Should a person at the end of life have a right to die to avoid a lingering end?
When you ask about a right to die, I assume you mean that there would be no law against the action. Everyone has the right to die, how can it be prevented.
Instead of having a right to die, the question should be whether it is ever right to die (i.e. suicide). Consider the following:
Seneca, knowing that Nero intended to take his life, had no
fear. He knew that he could defeat the Emperor. He knew that "at
the bottom of every river, in the coil of every rope, on the point
of every dagger, Liberty sat and smiled." He knew that it was his
own fault if he allowed himself to be tortured to death by his
enemy. He said: "There is this blessing, that while life has but
one entrance, it has exits innumerable, and as I choose the house
in which I live, the ship in which I will sail, so will I choose
the time and manner of my death."
For the Christian, I would say that we should depend on God's sovereignty and stay our own hand. We have the promise that we will not undergo anything that we cannot handle, and that God himself will provide the way out. There are many imaginable situations where the temptation to end your life would be present, but we are to resist temptation. It would be sinful for the Christian to commit suicide.
Balthasar Hubmair was burnt at the stake by Catholics in 1527. He told his followers that he would signal them if this death was bearable, and did so. Almost 20,000 people in Vienna came to Christ in the two years that followed his martyrdom. Would it have been better for him to kill himself, or to bravely suffer his execution?
For the non-believer, I would advise you to stay your hand for there is no relief in the grave.