To lower CYA, partial drain and refill is the easiest and cheapest option.

To lower Alk, Ben has a good process for that:

http://www.poolforum.com/pf2/showthread.php?t=191

However, given your hardness is fairly low, 160 may not be too bad. Assuming 70 degree water, saturation index is -.5 which means slightly corrosive. If you do lower your alkalinity make sure you get your PH up. Ph balance is about 7.7 with your current numbers. At an alkalinity of 120 your PH would need to be about 7.8 for balance. You may want to bump your CH up to about 200.