Hi Guys!
I got it. To allow only one user to access Alfresco's repository, and none of the others
Go to \tomcat\webapps\alfresco\WEB-INF\classes\alfresco
Open repository.properties file.
Change the property server.maxusers=1 // this will allow only 1 user to access the alf repository
You can also uncomment
server.singleuseronly.name=admin //By this you can only login as admin from your pc. No other login through any username will be possible from now on if this is uncommented.
Thanks