Q: I begin to ask myself "Who am I"?, eliminate the body as not "I", the breath as not "I", and I am not able to proceed further.
A: Well, that is as far as the intellect can go. Your process is only intellectual. Indeed, all the scriptures mention the process only to guide the seeker to know the truth. The truth cannot directless pointed out. Hence this intellectual process.
You see, the one who eliminates all the "not I" cannot eliminate the "I". To say "I am not this" or "I am That" there must the "I". This "I" is only the ego or the "I"-thought. After the rising up of this "I"-thought, all other thoughts arise. The "I"-thought is therefore the root-thought. If the root is pulled out all others are at the same time uprooted. Therefor seek the root "I", question yourself "Who am I?". Find out its source, and then all these other ideas will vanish and the pure Self will remain.
Q: How to do it?
A: The "I" is always there - in deep sleep, in dream and in wakefulness. The one in sleep is the same as that who now speaks. There is always the feeling of "I". Otherwise do you deny your existence? You do not. You say "I am". Find out who is?

aus
Be as you are
The teachings of Sri Ramana Maharshi
edited by David Godman
a Penguin Book