1.查看"维护计划"对象的ID

use msdb

select * from sysmaintplan_plans

select * from sysmaintplan_log

select * from sysmaintplan_subplans

2.根据ID号删除相应的"维护计划"

delete from sysmaintplan_log where plan_id = ''

delete from sysmaintplan_subplans where subplan_id = ''

delete from sysmaintplan_plans where id = ''