How can I unparent an object in an animaton? I was working on a baby project in which a toy trains takes a block (typically a cube). 

So I parented the block to the train and it moves perfectly from starting point to the stopping point.

At the stoping point I want this block to be un parented and start moving along a curve.



If I try to un parent it using Alt + P its jumps around as shown below:
Parenting can't be disabled during timeline. If you want this, you must use Child Of constraint instead. It has influence value, that can be animated.



Look also:

How do I &quot;parent&quot; objects?

Dynamic parent addon