Disable opening tabs in iTerm2 on when the application starts?
Close All windows and Tabs except only one(or arrange windows and tab you want), and then


Goto "Windows"->"Save windows Arrangement" 
"Preferences"->"Arrangements" set this as default 
"Preferences"->"General" and check open default window arrangement.


PS: iTerm restore all session when you disable the "Close windows when quit app" in System preferences