If you're like me, you've created various DITA2GO projects at different times for different purposes, and your Project Manager list has become a random mishmash of documents, document variants, and output formats.
One way you can sort and organize them is to open %OMSYS%\d2g\system\projects.ini (make a backup first) and rearrange them in the [Active] section. Their order here controls the order in the DITA2Go Project Manager "Projects" list.
CAUTION: Each project name has an index number for information in the other sections. Be sure to leave this number undisturbed.
Another approach is to use the Delete and Restore tabs in DITA2GO Project Manager. When you restore a deleted project, it's added to the bottom of the list.