How to clear notifications

 Hello ExpertsA week ago I cancelled few purchase orders through API however there are some purchase orders still appearing in the workflow as requires re approval though they are cancelled. Is there are any way to clear off or delete notifications through some program?

There are close to 500 notifications waiting in the workflow, if I don't clear these off from he list, approver is getting remainder notifications that the purchase orders are waiting for the approval.

I cleared all these notifications by creating the revision first by modifying the need by date on the PO using API and then cancelled them all using API again