As an account administrator, you can freeze or unfreeze a card instantly anytime. When a card is frozen, no payments can be made, which means the card is essentially made inactive temporarily.
On the web, you can do this by heading to the ‘Cards’ section, selecting the card you would like to freeze and in its setting, clicking ‘Freeze’. You can follow this same process to unfreeze the card anytime. On the mobile app, head to the ‘Cards’ section, select the card, and then “Freeze card”. Unfreezing the card works the same way.