Rejecting a submitted might not be an option as the data is already persisted in CRX. Since you have LiveCycle/AEM forms workbench, why don't you use LiveCycle workspace to create claim forms? You can have a reject button on the workspace.
In my case, i use the area AEM Sites with the drafts&submissions component for user that create a claim. This part is published.
In another area, Workspace (manage by Workbench workflow), a group of users check and elaborate the claims received.
The two areas are only connected when the user submit a form and the claim submitted is in the workspace area.
In workspace I've tried "reject button" but it doesn't work. In particular when i push reject button with my Workbench workflow, send an email of error to user that submitted claim. But i also want to move the rejected claim in draft tab of drafts&submissions component, otherwise a warning on submitted claim with explain message.