Extra cells removal. EXCEL

Hello,
Does anyone know how to hide unused cells in excel?

I have got a program that does all the matching for me, but everytime when i finished loading the program ( the program itself is successful), it results in a few thousands more empty cells after my last data.

What can i do the make excel Not producing the extra blank cells? And only give the number of cells that i need ( no blank cells after the last data).

Thanks.