It consistently uses Alt as a modifier to execute inverse operations. I to insert a keyframe, Alt+I to delete it. Ctrl+F to set a text filter/search, Alt+F to clear it. Ctrl+P to set parent, Alt+P to clear it. H to hide selected objects, Shift+H to hide unselected objects, Alt+H to unhide all. {G,R,S} to move/rotate/scale, Alt+{G,R,S} to reset transformations. It's not exactly industry standard, but internally consistent that makes learning it easy.