Since a reconciled check cannot be reversed, you would need to restore the division from a backup prior to the check being reconciled. 

If a restore from backup is not possible, a solution might be to:

  1. Purge the reconciled obligations in the check. (49891)
  2. Re-enter the obligations with a manual check. (55329)
  3. Reverse the trace reports created when posting the manual check.
  4. Keep records for auditing purposes.