Purge table - older than four weeks data

Hi Experts,

i have DB named "Test_Data" -> under this DB i have tables like a,b,c... and so on.

in all the tables i have column "Week_no" and all table will have data, week_no wise.

I want to write the procedure to purge the tables which are having older than 4 weeks data.

in my table week_no will be like this "201409" and so on.

this procedure we will run weekly once.

Can any one please help me to write SQL procedure..