Short answer: No, authors can’t change the submission type / track of their submissions.
Full explanation: Different submission types or tracks often have different requirements and deadlines.
Therefore, authors will have to withdraw the old submission and create a new submission with the correct submission type / track.
However, administrators or chairs can edit the submission type / conference track.
Please go to:
Overview => Submissions & Reviews => List of Submissions
... and click on "Edit" in the right column "Actions" to update the submission and select another submission type or track.
You find the option "Submission Type / Conference Track" at the top of the edit page.
Please be aware that you might have to add more information in fields designated solely to the new submission type / track.