While cutting defense will decrease "Total Defense Cost", and increasing CEO development will increase "Income from Enterprises", neither will affect the "General Cost of Government" line item.
The "General Cost of Government" can't be directly manipulated. However, it's based off the size of your population and the number of countries in your empire. Increasing the number of countries in your empire over 10 will start dramatically increasing this cost. I haven't analyzed the cost versus population size significantly, but I believe it's fairly linear among reasonable population sizes.