According to Bohr's theory, As we go further away from the nucleus the velocity of an electron,

According to Bohr’s model, the angular momentum of an electron is quantized.
So, $\mathit{mvr}=\frac{\mathit{nh}}{2}$
$\Rightarrow v=\frac{\mathit{nh}}{2\mathit{mr }}$
From this expression, the velocity of electrons decreases as we go away from the nucleus. This is because of the decrease in the nuclear force of attraction. 

Electrons require less velocity to counter balance the nuclear force of attraction as we move away from the nucleus. (decrease the nuclear force of attraction).