you can check the Event Log entries on the box where you installed the SQL Data Sync Agent.
Event Viewer->Applications and Services Logs->Sql Azure Data Sync Preview
or Event Viewer->Applications and Services Logs->Data Sync Service
or you may also try turning logging in verbose mode.
Open LocalAgentHost.exe.config in notepad. This file should be present in your installation directory.
a) Uncomment the section that is currently commented < !-- < switches> < add name="SyncAgentTracer" value="4" /> < /switches> < trace autoflush="true" indentsize="4"> < listeners> < add name="myListener" type="Microsoft.SqlAzureDataSync.ClientLogging.DSSClientTraceListener, Microsoft.SqlAzureDataSync.ClientLogging, Version=2.0.0.0" initializeData="DSSAgentOutput.log" /> < remove name="Default" /> < /listeners> < /trace> -->
b) Stop and restart SQL Azure Data Sync Preview Windows Service. Now you would find the detailed logs in files named DSSAgentOutput*.log.
If you delete the sync group and the tables are part of other sync groups or you have other sync groups, the deprovisioning will not completely remove everything, just that particular sync group definition.