Schema::dropField

public Schema::dropField($table, $field)

public function dropField($table, $field) {
  if (!$this->fieldExists($table, $field)) {
    return FALSE;
  }

  $old_schema = $this->introspectSchema($table);
  $new_schema = $old_schema;

  unset($new_schema['fields'][$field]);

  // Handle possible primary key changes.
  if (isset($new_schema['primary key']) && ($key = array_search($field, $new_schema['primary key'])) !== FALSE) {
    unset($new_schema['primary key'][$key]);
  }

  // Handle possible index changes.
  foreach ($new_schema['indexes'] as $index => $fields) {
    foreach ($fields as $key => $field_name) {
      if ($field_name == $field) {
        unset($new_schema['indexes'][$index][$key]);
      }
    }
    // If this index has no more fields then remove it.
    if (empty($new_schema['indexes'][$index])) {
      unset($new_schema['indexes'][$index]);
    }
  }
  $this->alterTable($table, $old_schema, $new_schema);
  return TRUE;
}