There is not much information on omserv running on port 764. By doing trial and error and using the lsof command, I found that omserv is actually nfslock. If you want to turn off this service (I surely do, since I don't know and use this service), issue the command:
chkconfig --levels 2345 nfslock off
This will remove the autoexecute of the nfslock. Afterwards, issue the command to stop the process:
/etc/rc.d/init.d/nfslock stop
To verify if you have stopped the service, type the command:
nmap localhost
