[root@RHEL6X64MMTM ~]# vncserver

New 'RHEL6X64MMTM:7 (root)' desktop is RHEL6X64MMTM:7

Starting applications specified in /root/.vnc/xstartup
Log file is /root/.vnc/RHEL6X64MMTM:7.log

[root@RHEL6X64MMTM ~]# vi /root/.vnc/RHEL6X64MMTM:7.log

Fri Jan 8 08:36:44 2016
vncext: VNC extension running!
vncext: Listening for VNC connections on all interface(s), port 5907
vncext: created VNC server for screen 0
MainThread 2016/01/08 08:36:47.3318 (sabayon-apply): No profile for user 'root' found
No profile for user 'root' found
MainThread 2016/01/08 08:36:47.3321 (sabayon-apply): Fatal exception! Exiting abnormally.
MainThread 2016/01/08 08:36:47.3324 (sabayon-apply): Traceback (most recent call last):
File "/usr/sbin/sabayon-apply", line 149, in <module>
sys.exit (util.EXIT_CODE_NO_USER_PROFILE)
SystemExit: 3


anyone please help me to resolve the issue

Did you follow these instructions? I found them by googling for your error message.

http://dingyichen.livejournal.com/5230.html

In short, your problem is not VNC, but the way you set up your desktop. It can be solved by creating a profile for root with Sabayon, an old and probably obsolete tool for managing desktop accounts.