I suppose you created a time condition pointing to that ring group some time ago, right? Maybe there was an issue with that specific version.
You may try this:
select d.id from ombu_destinations as d
left join ombu_destinations_category odc on d.category_id = odc.id
where odc.module_id = (select module_id from ombu_modules where name = 'ring_group')
and d.module_id = (select module_id from ombu_modules where name = 'time_conditions')
and d.index = (select ring_group_id from ombu_ring_groups where extension = '100');
The script above will return you the destination IDs associated with the ring group 100, so, now that you have the ID, you only need to delete the item:
delete from ombu_destinations where id = ?
The ID will be the value or values returned by the first query.