There is no date field in this table but the "input_file_name" contains date & time.
hive> desc mi_data;
Is this an external table? if it is an external table then write a perl/shell script that runs daily based on a pattern it will remove files older than a certain date.
If it is not, and if it is a managed table with ORC/Parquet format, then it depends on how you load the table. While loading the table you could setup logic to populate the date in the table partition by that date and as @Avijeet Dash mentioned drop the partition that is 7 days old.