The Attachments box can be added or deleted from the form. By default, a new form will include this box.
To Remove the Attachments box:
Right-click in the title area of the Attachments box and choose "Delete".
Once it is removed, it will show up in the Tabs/Section area of Form Controls.
To Add the Attachments box:
The box can be added back in by dragging and dropping the control from the Form Controls box to the form.