Hi Shahin,
It seems that this key figure is populated with the macro help. Please check the macro for your planning book (T.Code - /SAPAPO/ADVM) and you will understand how the values are calculated.
To delete you have to know the category of the order. To find the category double click on the value (or right click) and choose details. Then go in t.code /SAPAPO/DELETE_PP_ORDER or /SAPAPO/RLCDEL to delete the orders for the desired period.
Thanks,
Regards, Marius