Calculation of DC power drawn by circuit in Class A power amplifier
The power for an amplifier is provided by the supply. The power a supply delivers is its own voltage (that's why we take \$V_\text{CC}\$) times the current drawn from it.

For a Class A power amplifier, with no input signal, the DC current drawn equals only the collector bias current, \$I_\text{CQ}\$, because the current drawn by biasing resistors is ignored.  

So, the DC power that the supply delivers equals to:
$$ P_\text{dc} = V_\text{CC} \cdot I_\text{CQ} $$