Acc. to Wikipedia, When a pawn advances to the eighth rank, as a part of the move it is promoted..."
This doesn'clear whether I am obliged to make this move if I am at eighth rank or it's over me?
Yes, it is obligatory.
From FIDE's Laws of Chess §3.7e (Link):
e. When a player, having the move, plays a pawn to the rank furthest from its starting position, he must exchange that pawn as part of the same move for a new queen, rook, bishop or knight of the same colour on the intended square of arrival.