In short text box, or in number column, there is “x” button in the window, if you press it your data will be removed, It is kept in activity however, sometimes it happens accidentally without realizing it, just one click on "x’ button is enough. there must be a confirmation dialog box saying "are you sure you want to clear data ? " this is essential.
Due to missing this feature I am obliged to use long text box, which is not always convenient.