HR Learn does not allow you to remove completed course records from a user's transcript. You do have the ability to revoke an awarded certificate, but that does not mean that the course completion is going to be removed from the user's transcript that is associated with the certificate that is being revoked.
If the course enrollments happened within the system, you can reset the enrollment on a user's profile and delete it.
If the record was placed on the user's transcript as part of an activity import, you can remove that entire import. Select the import file you want to remove and select the "delete selected activity import(s)" link at the bottom of the page.
Keep in mind that if the import file contained records for other users, and you want only a single record removed; the Team will have to remove it on the backend under billable time.