how to Delete a Organisational unit

Hi Experts,

I have created Organisational structure,with one parent/root organisation and 5 sub organisational units. I want do delete one now because my clients are closing that unit. I am trying to delete it but, I am able to delete only the positions but the Object "O"/ Organisational unit i am not able to delete.

even while hiring an employee, the position field is displaying the positions of org unit which i don want.

I tried through pp01 and ppoce_Old

please help me, this is my first project.

Thanks in advance

Smitha