Cancel parttial PO Line

 Hi All,

I create 2 requisition

Req1 Line1 Item1 Quantity 10

Req2 Line 1 Item1 Quantity 5

I received 2 receipt Quantity lines

Item 1  Quantity 10

Item 1 Quantity 5

I return Item 1 Quantity 5 to supplier

Do I need to cancel partial line in PO (I'm not sure it's possible) to have my encumbrances OK?

How can I do that?

Any note or document on this subject will be greatly appreciated

Thanks

Best regards