Infurnia does not support moving a design file currently. However, you can copy the design file from one project to another project.

Refer these articles to understand the process,

Copy a design file:

http://help.infurnia.com/en/articles/8290616-how-to-copy-a-design-file

Rename a design file:

http://help.infurnia.com/en/articles/8290624-how-to-rename-a-design-file

Delete a design file:

http://help.infurnia.com/en/articles/8290627-how-to-delete-a-design-file