I read the https://www.odoo.com/forum/help-1/question/in-pos-only-display-on-hand-quantity-47586 and using the method : 

[['sale_ok','=',true],['available_in_pos','=',true], ['qty_available' , '>', 0]],

It works, the non available products did not appears... but sadly the SERVICE that I provided're gone.... 

How to show the services and unshow the non available products....

PS: I'm using in in a Computer store where we sell products and provide services for installation... need to unshow the non stock products and show the services