How can I disconnect the link of component with parent?

Case 1)

I make a intersection curve using two bodies

then I want to delete the bodies (not hide)

but if I delete one of the bodies, the curve die.

Is there a good way to use the curve and delete bodies?

Case2)

I sketch a circle on A-body and make an extrude (named B-body) with the sketch.

Then

if I move A-body, the sketch also moves and B-body too.

If I want to move only A-body (not moving B-body), how can I do this easily?

..So I want to disconnect the link with parent component ( ex. intersection curve<->bodies , sketch <-> body )

Please help me with simple method.

Thanks a lot.