You may have the Action Rule set to "Delete file from (local folder) After Transfer" for the condition when you "Transfer file from (local folder) To (remote folder)". Check the Action Rule you have set for Local and Remote folder synchronization. You can change the Action Rules by right clicking the profile that you are synchronizing and selecting Edit Profile]Transfer tab]Action Rules.
For more information on Action rules, you may visit the help page on
Action Rules
DeskShare - Support