Hello Aditi,
That is correct, if you delete the PV in ECC is does not update the PPM in APO. you will have to delete the PPM in APO manually using /SAPAPO/PPM_DEL or /SAPAPO/SCC03 transactions.
Before you delete the PV in ECC, change them to Locked status, in the CIF transfer it will make the correspond PPM as inactive. Now in /SAPAPO/PPM_DEL you can select all the inactive PPMs and schedule it in the backgroung.
However note that the PPM cannot be deleted as long as it is being used/reference by any object. So you need to clean up before the deletion program can delete the PPMs.
You can use below reports to delete the orders
/SAPAPO/DELETE_PP_ORDER
/SAPAPO/RLCDEL
And now you can delete the PV in ECC.
Regards,
Abhishek Rai