Need to cancel/Delete the Rebate Credit memo request

Hi,

Requirement: I want to reverse the partial rebate settlement.

Because some reason user made a mistake by creating partial settlement. Now he wants to reverse that entry and the same value should be reverted back to Rebate agreement.

Cancelled the Rebate credit memo (VF11)

Tried to delete or reject the Rebate credit memo request ( VA02)  BUT system is NOT accepting at all.

Please advise me how to solve my problem?

Searched in google but no luck.

Thanks in advance.

Regards,