The best way to deactivate sub-accounts is to do so from your ACCOUNT settings (https://unity.scanpower.com/account).
Here, you can turn them off and on whenever you'd like, and even edit the email address/password tied to the account(s).
** Please Note: Turning off a sub-account does not cancel the portion of the subscription you are paying for which gives you sub-account access. To do this, you must go to SETTINGS > ACCOUNT > SUBSCRIPTIONS and unsubscribe from the sub-account subscription (normally a LIST add-on). For LISTPro users, to cancel sub-accounts you need to downgrade your subscription to either ScanPower ACE or LIST+MOBILE.