My BIL went in the very early morning, he wasn't on any life support, just went naturally at his time.
His son was sitting with him and told us - "He took a breath and let it out and that was it..."

It is up to you as to how you feel about being there {in the room}, but since you have spent so much time you might have a better closure if you are near so you can say a goodbye before they take the body.

I only add this because when we got to the home where BIL had passed it was very strange to not see him in the bed where we had been caring for him. They called the county right away in the middle of the night and the body was taken, so we didn't get to see him a last time.
Until the funeral - but that is a different situation {public} and his was 4 days later.
I would have rather touched his hand and said goodbye before the body had been taken away.