From your myasics.com My Plan tab, click on Plan Options and select Terminate Plan
On your iPhone app, tap on the My Plan tab and tap the gear icon in the top right-hand corner. Select Terminate Plan and confirm your choice!
On your Android app, tap the 3 white lines in the top left hand corner of the screen and choose Plan. Then tap the 3 white dots in the top right hand corner of the screen and choose Terminate Plan