Hi Soma,
Please run report S_ALR_87013019 to find out the relevant document no, for particular posting which has created assigned value either actual or commitment.
This will give you all the details.
And if you want to delete COSP records proceed as -
1. RKACSHOW : Enter order to find out OBJECT NO.
2. Run report RKPLNC27 (refer to note 549760 ) to delete zero records in COSP (with parameters : object number, fiscal year, version)
Please keep in mind it will delete the entries in COSP which has zero values.
Thanks & Regards
Pooja Gaur