show variables that aren't strongarmed. delete variables from database that are.

gistfile1.php

foreach (ctools_export_load_object('variable') as $variable) {
  if ($variable->export_type == EXPORT_IN_DATABASE) {
    dpm($variable->name);
  }
  if ($variable->export_type == EXPORT_IN_CODE) {
    variable_del($variable->name);
  }
}