Hi i have this matrix 

e.g

```
import numpy as np
a= np.arange(9).reshape(3, 3)

[[1. 2. 3. ]
 [4. 5. 6. ]
 [7. 8. 9. ]]

```

how do i delete the bottomost value of a selected col (e.g col = 1) and the rest of the values on top gets pushed down, and if there is an empty space, put "0"

so the matrix becomes

```
[[1. 0. 3. ]
 [4. 2. 6. ]
 [7. 5. 9. ]]

```