In training you will be asked to reconnect your Low Pressure Inflator while still underwater. In the event of a real stuck inflator button it is unlikely that you'd want to do that. However, it is possible that you will resolve the problem of the sticking inflator button once the hose is disconnected and that you'll want to reconnect the hose. This step is quite similar to when you connect it when setting up your gear, but may be more difficult underwater.
Gripping the hose with your left hand, use your thumb and index finger to pull the slide lock back.