方法一:
ALTER TABLE kuming.tableName DELETE WHERE toDate(insert_at_timestamp)='2020-07-21';
方法二:
ALTER TABLE kuming.tableName DELETE WHERE insert_at_timestamp<=1596470399;
方法三:(当前两种方法分区数据没有删除掉的时候可以用方法三)
ALTER TABLE kuming.tableName DROP PARTITION '2020-08-03';