Assuming you have a "BKUP" Directory in Drive K and the backup files are with the extension .bak and you need to delete all files with .bak in that directory.
Create a batch file that deletes all the required files.
Deleting all files with the extension .bak would need a command such as "DEL K:\BKUP\*.BAK".
You need to create the batch file and have it run in a SQL Server Job scheduled daily.
i have a folder named BACKUp inside that there are many subfolders with the name of servers. so will the command "DEL K:\BKUP\*.BAK" delete all the .BAK file of subfolders