Pretty simply, my friend. In the properties of your character, look for Behavior.
Click in add/edit behaviors, a pop-up window appear.
Click in the plus icon to add a new behavior.
Look for "Fade" and add it.
Now in Properties, look for the Fade properties:
Change "Active at start" to No
Now in events:
Condition = Colides with object = Action = Start Fade
Now your character will fade out and destroy. You can change the fading speed at the properties too.
I hope I could be able to help you.