Place the Oobleck into an airtight container or a zip-seal bag. Take it out again later and have fun playing with it. If you're done with the Oobleck for good, DO NOT throw it down the sink, or it may clog your drain. Throw it in the trash instead. You'll likely need to re-add water to your oobleck to play with it a second time.

TL;DR in Vietnamese:
Bảo quản Oobleck.