Google Slides: Hide Side Panel
Drag the bookmarklet below to your bookmarks. When you’re working on your Google Slide presentation, or playing a game where you want to hide the sidebar, simply click it to hide (or show) the slide panel:
If you refresh your page, the sidebar will come back. If you want to make your main Slide page bigger/smaller, use "Ctrl +" to increase the size and "Ctrl - " to decrease the size. If you want to revert the size changes, press "Control & 0".