Your banneton is only intended to let the dough rise and must not be baked. Moisture might be extracted from the dough during proving, so after use, your banneton should be brushed out and stored in a warm and well-ventilated place in order to prevent mould formation, eg on an open shelf in your kitchen. If you need to stack more than one banneton for storage, they must be completely dry prior to stacking.
You can also use the residual heat from your oven after baking your bread, at approx 100-120 degrees Celsius to dry your banneton. In this way, they dry faster without being damaged and at the same time any germs are killed.
Joe finds dusting the bannetons with rice flour preferable to wheat flour as it is better at preventing the dough from sticking.