field_purge_instance($instance) Delete the row for this instance from the field_config_instance table. It is assumed that all data for the instance has already been deleted. Read more about field_purge_instance($instance)
field_purge_field($field) Delete a field's row from the field_config table. Throws an exception if there are still instances of $field in the field_config_instance table. Read more about field_purge_field($field)
field_info_cache_clear() Clears the field info cache without clearing the field data cache. Read more about field_info_cache_clear()
