On many, if not all AAC systems, there is a feature called "Hide/Show" or "Vocabulary Builder." The purpose of the "hide/show" feature is to allow the person programming the device to minimize the visual field of vocabulary. If you want to reduce the number of icons on the screen temporarily to teach a motor plan and decrease the visual distractions, you may want to temporarily hide some of the vocabulary.
It is important that this is a temporary strategy. We are not hiding items we don't want them to request; we are not taking away their ability to communicate their thoughts, feelings.
Check out the video below to see the Hide/Show features in TouchChat, Proloquo2Go and LAMP.