closeToast = id => {
    setToasts(
      toasts.map(toast => {
        if (toast.id === id) {
          return {
            ...toast,
            isShown: false
          }
        }

        return toast
      })
    )
  }
This will set isShown on the Toast which will close the toast.
It won't remove the toast until onExited triggers onRemove.