Sorry, but what are you trying to achieve?
When is the object supposed to be destroyed? When you press Enter after it has collided?
If that is the case, you can simply store the collided object's UID in a variable (global or instance doesn't matter).
You do so by adding an event "Player: On collision with [object]".
Underneath that, add an action "Set value "collisionUID" (your variable) to [object].UID".
(Since the colliding [object] gets picked by the event, the correct object's UID will be stored.
Now, you add your keyboard event "On Return pressed".
As a sub-event, add an expressional picking condition, picking [object] with the expression [object].UID = collisionUID.
On that condition, add the action [object]: Destroy.
You can also add a condition to the keyboard pressing event: "If 'CollisionUID' is not 0" and an action after the destroying action: "Set 'CollidionUID' to 0".
This prevents destroying an [object] that already has been destroyed.
If you need further help or a .capx, give me a shout.