"000871 : <value>: Unable to delete the output <value>."
A dataset with the same name as that specified for the output already exists, and it could not be deleted during execution.
Solution or Workaround
Verify whether the existing dataset is being held by another application (another ArcMap or ArcCatalog session or the file explorer) and thus is locked. If so, either release the dataset from the application or close it.
Check that write permission has been enabled to the output location.