When a Primary account requests for termination (including port out), all Sub accounts will automatically be converted into the 20GB plan by the end of the month.
When a Sub account requests for a termination, it will not affect the Primary or other sub account(s) in the same Family Plan. If all sub accounts are terminated, the Primary account will continue to remain as the Primary account in the Family Plan, with revised monthly rate.
*Please make sure you communicate with your other accounts before the termination.