How Long Till Crestor Is Out Of My System..I Want

How long till crestor is out of my system..I want to see if low carb and low fat diet with increased exercise is enough to lower my cholesterol of about 212.,,I am a post menopausal active female age 63. i usually walk a brisk 3-5 miles per day in gentle hills...deep.east texas.My happy cholesterol is between 60-70 usually.These numbers are prior to rx.