There is no add nor remove option within todo window, right click also do not bring menu specific to this window. I think it is poor user interface design. Also, after few days when I finally found the option how to add something to "todo" list to my surprise everything is added not only to the 'todo' window but also to the code. I do understand that it is useful to have this working this way but sometimes it would be also useful if I could add items just on the todo list - without adding them actually to the code. But there is no such option listed on this window. I think that this window needs to be improved.
Thanks