@LizzieB -

Unfortunately there is nothing that can remove it within the new responsive designer. The only way to remove it would be to remove the element from the page or hide it within the CSS. 

This is how you would do it within the Classic designer for Nintex forms, but that option is not currently present within the new responsive designer.

Hope this helps!

You say the only option is to remove the element from the page or hide it with CSS - So then, how can we hide it with CSS? I don't see anything in the new responsive designer that gives me the option to enter in custom css or remove any elements from the page?

We need for the people who are entering into the form to not be able to see the sharepoint list behind it... I know I can easily redirect on the cancel button at the bottom left and on the submit button at the bottom right, but that leaves the close button at the top left that still leaves us vulnerable.

If your need is that the user can't view the items submiting, you ave sevral option.

Option one : Use the native SharePoint. In advence settings of your list, you have "Item level permission" to set at "Read items that were created by the user". With that you user will have, by default, just read permission of his items.

Option 2: use 2 lists. You users fill/create items in liste one, you have a workflow triggered at item creation. This workflow create an new item in the list two (with value of the item just added), and remove remove you current item.

Option 3 (Best way):

Use NWC to create your item. With Nintex licence, you can have the product : Nintex Workflow Cloud. So in NWC : Creates a worklfow (Started by a forms) that will create your item in your SharePoint list. With that way, you does'nt need to allow users to acces to you SharePoint list (It is the nwc worklfow that will access it.), you just need to give the URL of the NWC Form, your user will fill it and they will never access to your SharePoint List.