Delete diagonals of zero elements

One way using numpy.pad:

n = my_array.shape[1] - 1
np.dstack([np.pad(a, (i, n-i), "constant") 
           for i, a in enumerate(my_array.T)])

Output:

array([[[45,  0,  0],
        [ 4, 48,  0],
        [10,  4,  1],
        [37, 20, 40],
        [25, 24, 22],
        [ 0, 25,  7],
        [ 0,  0, 13]]])