You can download a template or empty design from the Online Designer to do your design offline.
Download sweater template
Click "Share design" and then "Download" left below the link. Pick desired sweater size before downloading.
Empty / erase design for a blank template
Click on "Color" on the left to remove the pattern and make the design uni color
Other elements in the design (cliparts, text, uploaded content) are not deleted by removing the background pattern.
Either remove them with the trashcan icon at the element. Or if there are or a lot of elements, removing is quicker via the "x" in the layer list
Send enquiry, save / share design:
Send the current state of your design as enquiry with the button "Send enquiry", top center / right in the Online Designer.
Or save resp share your design with the "Share design" button. Copy the link displayed to reopen the design later.