***Can any one provide me the correct link for SEPM 12.1.6 which should support Widnows 10, 7 with 64 bit OS ?***
No,Below OS requirement.
Operating system (Desktop)
- Windows XP (32-bit, SP3; 64-bit, SP2; all editions except Starter and Home; all patches applied, including Internet Explorer)
- Windows 7 (32-bit, 64-bit, RTM and SP1; all editions except Starter and Home)
- Windows 8 (32-bit, 64-bit)
- Windows 8.1 (32-bit, 64-bit)
- Windows 8.1 update for April 2014 (32-bit, 64-bit)
- Windows 8.1 update for August 2014 (32-bit, 64-bit)
Operating system (Server)
- Windows Server 2003 (32-bit, 64-bit, R2, SP1 or later; all patches applied, including Internet Explorer)
- Windows Small Business Server 2003 (32-bit; all patches applied, including Internet Explorer)
- Windows Server 2008 (32-bit, 64-bit, R2, RTM, SP1, and SP2)
- Windows Small Business Server 2008 (64-bit)
- Windows Essential Business Server 2008 (64-bit)
- Windows Small Business Server 2011 (64-bit)
- Windows Server 2012
- Windows Server 2012 R2
- Windows Server 2012 R2 update for April 2014
- Windows Server 2012 R2 update for August 2014
https://support.symantec.com/en_US/article.TECH230602.html
***also link to remove existing sophos 10.3 antvirus from pc with SEPM console..**
Third-party security software removal in Endpoint Protection 12.1
https://support.symantec.com/en_US/article.TECH195029.html
See below thread
https://www-secure.symantec.com/connect/forums/uninstall-other-security-software