Clearing the selection-screen fields after the execution of the program?

Hi all,

I have a cost-center group & cost center fields in the selection-screen. And in the at-selection screen event, i populate the cost center fields for the given cost center group in the selection-screen. After the execution of the program, when i come back to selection screen, i see those populated cost center ranges for the cost center group in the selection screen , which i don't want to see. So how to clear those fields?

Please do help me.

Thanking you all in advance.

Regards,

ABAPer