You can change the order of slides in the player menu for an Articulate Storyline course. However, it won't affect the actual order in which your slides display. Slide order is determined by the trigger assignment for the Next button.
Similarly, you can hide (remove) a slide from the player menu, but it'll still display in the published course at the appropriate time.
To learn more about editing the player menu, see this tutorial. To learn more about managing scenes and slides, see his tutorial.