If you ever need to stop accepting new subscriptions for a list, whether temporarily or permanently, you can do so by deactivating the list.
First, navigate to the list in Campaignzee.
Next, click Settings, then click Deactivate List in the dropdown.
Read the warning that is displayed. If you are sure you want to deactivate the list, click Deactivate List.
Your list is now deactivated. The hosted signup page will no longer show, and any submissions with the embedded form will not work. You should remove the signup embed code from your site.