From what I can tell the only way to change a object's parent is by dragging and dropping in the Scene editor, which I find can be a little messy, too easy to drag to unintended parent, then having to fix that.
I Suggest 2 Places where a simple remove parent / make parent command could be located:
#1 By right clicking a object in the scene editor -> remove parent / make parent or
#2 In the main toolbar / Edit menu. -> remove parent / make parent
Also allowing for multiple selections in the view port or editor, where the last selection would be made as a parent, if the make parent button was toggled would be useful.