When hydraulic Power Take Off (PTO) is used to convert the mechanical energy of a wave energy converter into a more useful form of energy, the PTO force needs to be controlled. Continuous controlled variation of the PTO force can be approximated by a set of discrete values. This can be implemented using either variable displacement pumps or several hydraulic cylinders or several high pressure accumulators with different pressure levels. This pseudo continuous control could lead to a complex PTO with a lot of components. A simpler way for controlling this hydraulic PTO is declutching control, which consists in switching on and off alternatively the wave energy converter's PTO. This can be achieved practically using a simple bypass valve. In this paper, the control law of the valve is determined by using the optimal command theory. It is shown that, theoretically when considering a wave activated body type of WEC, declutching control can lead to energy absorption performance at least equivalent to that of pseudo-continuous control. The method is then applied to the case of the SEAREV wave energy converter, and it is shown than declutching control can even lead to a higher energy absorption, both in regular and irregular waves.