You must disable notifications on the other apps, or else you will get duplicate notifications!
Most people will place Beeper on their smartphone home screen, and move all other chat apps into a folder. You should keep all chat apps installed, just in case you need to use a feature that is not supported yet in Beeper.
WhatsApp and Signal apps MUST be kept on your phone! Do not delete these apps while they are connected to Beeper. Deleting WhatsApp and Signal apps will result in a disconnection. This is a limitation of those specific networks.