How do you lower the compression ratio of an engine?

How do you lower the compression ratio of an engine?
There are several means by which the compression ratio of an engine might be reduced although all involve extensive mechanical rework to accomplish.
1) Remove the heads from the motors and grind the compression chambers of the head(s) to make the area larger.
2) Install replacement pistons that have a different shaped piston top (usually a larger "dished" area)