title: NKIssueContentStatus change to NKIssueContentStatusNone
body: <p>In my app I have a “Delete” button which should delete the downloaded file and in background I want to change status to NKIssueContentStatusNone from NKIssueContentStatusAvailable.</p>
  
  <p>I know the property is read only. I would like to ask what function to call to change the status from NKIssueContentStatusAvailable to NKIssueContentStatusNone.</p>
  
  <p>Thanks!</p>