How I can remove a duplicate game in my collection
Go to My Collections in the top-right menu. When you hover with the mouse over a game, several commands appear, among which Remove.
In the hover menu does not appear remove option
I would also like to ask the same question.
Are you trying to right-click by any chance? Just bring the mouse cursor over the game. (You do need a mouse, not just a touchscreen.) Come to think of it, what browser do you have? It could be a compatibility issue...