If you used the default installation procedure you may uninstall the program using the same method all software is uninstalled in Windows.
If you downloaded the no-install version, you need to find the folder you originally chose to locate the program, and delete all the files.
If you are using a recent version of SyncBack then uninstalling will not delete your profiles (unless you give permission to do so during the uninstall process). However, you before uninstalling, you may wish to export your profiles. All versions of SyncBack can safely be installed over an existing installation. By doing this, you will ensure any profiles you have created continue to be active.
Lastly, make sure that SyncBack is not running while you attempt to uninstall. Remember that SyncBack can be seen in the taskbar on the lower right when active (you may need to click the little left pointing arrow to see the SyncBack icon). You may have also created a scheduled task which you will need to disable if uninstalling. Using the Task Manager you can also check to see if the process SyncBackPro.exe, SyncBackSE.exe or SyncBackFree.exe is currently running.