Script for cleaning data on a regular basis

[a bv]

Hi,

I have a mysql running having a database on it.  Database contains
tables (structures?) which gets montly data , and these tables are
named as

name1_name2_ yearmonth . I only want to have the whole database system
for last 2 years, and automaticly clean the data which became more
than 2 years old , so i need a script for this (shell, php etc) . Can
you please help me for this script ? and also which mysql command must
be used drop, trunk?

Regards