Sorry, my mistake...

Code:
SET @configuration_group_id=0;
SELECT @configuration_group_id:=configuration_group_id 
FROM configuration_group
WHERE configuration_group_title= 'ZX Slideshow Configuration'
LIMIT 1;

DELETE FROM configuration WHERE configuration_group_id = @configuration_group_id;
DELETE FROM configuration_group WHERE configuration_group_id = @configuration_group_id;
Please try again.