If there is less contact between the gas and liquid, the reaction will proceed at a slower rate. Water displacement works well for this. Shake the bottle. Set it down and watch it collapse. If demonstrating importance of surface area, prepare two bottles and do not shake one of them.
Sodium hydroxide is corrosive.
Wear gloves and goggles. Do not re-use the soda bottle. Sodium hydroxide will decompose the PET over time. Rinse water may be flushed down the drain with excess water. The bottle can be put in the regular trash.