I swear it should be a way to disable this feature in unity 2018.3.
Anyways go to Canvas, double click on prefab and inside prefab I delete a child, and now there is no option lie the original way to apply change, so I click arrow to get on of nested prebabs and the child I delete comes back…
help please, I cant believe we are force to use this feature if we want to update to 2018.3. So messed up.