Unable to delete/withdraw learners from an offering whose activity status is completed & progres 0/0

Summary:

Dear All,

Our customer have created one course and added the offerings details and tagged the learners at offering level. However after sometime they have recognized that activities were not created and then we have created activities and click on 'Reconcile Learning Assigments.' Now the learners who were already tagged at offering level, their status shows completed and progress 0/0. For the existing learners the activities are not added and now we need to withdraw or delete these learners, but the option is grayed out. Also 'Undo complete' option does not make any change to these learners.

Can someone let us know what can we do to resolve such issue?