Best way to reduce compression ratio?

Camshafts don't bleed off compression. You can choose a camshaft with a later intake closing point. That makes the cylinders begin the compression later. That means since the compression is not begun as early, there will be less cylinder pressure. You lose nothing. You simply begin compressing the mixture in a different place. What camshaft do you have now? A cam change would be the easiest and cheapest way.