How to delete a request in EDM if the submitter and owner of the request are no more user in EDM

We want to recall and delete some requests in EDM. There is no approval policy active on such request. But still the admin is getting notifications to approve the request and when he opens it to approve/reject the request it throws error. The submitter of the request is no more a user in the application and delete option is throwing below error. How can we delete these requests which are not required?

Thanks,

Vidhi Nenwani