Hello,
Check this:
How to change a Symantec Endpoint Protection client from unmanaged to managed
http://www.symantec.com/docs/TECH102322
1.Copy of the file Sylink.xml from the server from C:\Program Files\Symantec\Symantec Endpoint Protection Manager\data\outbox\agent\
2. On the client computer , click Start > Run, type smc -stop, and click OK.
3. Copy the Sylink.xml into the C:\Program Files\Symantec\Symantec Endpoint Protection folder, and replace any existing Sylink.xml file.
4. Click Start > Run, type smc -start, and click OK.
Hope that helps!!