My tri-indicator reads 35psi when in operation. The pressure release valve is set for 30 psi.

I have a steady drip when the boiler is running.

How do I go about relieving some of the pressure?

I believe I have 2 zones, there are 3 sets of pipes running up away from the boiler.

I wanted to confirm with someone before I shut-off the water and draw off a gallon at a time from each vavle/outlet until the operating pressure holds south of 30 psi.

Confirmation or Corrections appreciated.

You need to locate the pressure reducing valve and adjust it (not that simple for me to tell you where it is since installer can place it almost anywhere and there are several very different looking types). Boiler should be aprox 12 psi cold and 18 psi hot. If it is 12 cold and then does up to 30 psi when hot, you have a faulty expansion tank.