A shell is fired into air at an angle θ with the horizontal from the ground. On reaching the maximum height,

At the highest point during its trajectory the body will only have the horizontal component of velocity given by $\mathrm{ucos\theta }$.

So the kinetic energy is not equal to zero.

As the potential energy of any body is given by the virtue of position We cannot conclude that the potential energy is zero or non zero. We can only conclude that the potential energy of the body changes by mgh, where h is the maximum height attained by the particle throughout the motion. But we