When you're finished using your earbuds you can manually power them down by holding both touch controls at the same time for 3 seconds, the voice prompt will say “Power Off”. Alternatively, placing them in the charging case will also power them down.
If the earbuds are left out of the case and connected to a device but with no audio or operations for 10 minutes, they will power down automatically.
If they are powered down whilst out of the case, hold the touch control for 3 seconds until you hear “Power On” and see a LED display.