How do I get out of the High Roller Room

If you're in the high-roller room you can just click on the 'X' icon in the upper right corner of your screen to exit the high-rollers club room.
In the Main Lobby, the regular slot machines are placed after the high roller ones. When you're in the main lobby screen, you just need to swipe right and scroll further in your screen past the high-roller slots to access the regular games.