How to delete the log in screen on start up?

Open system preferences > click on users and groups > click the lock icon and enter the credentials ( if it is an admin account , enter admin name and password ) .

Its your choice to select the options from login options , some users check the box of name and password only so that when system is started in the login window only name and password is visible .

System Preferences > Users & Groups > Login Options

Make sure to unlock the Lock at the bottom Left

The original poster has already said they Do Not want to have the login screen at start up, the question was ably answered one and a half hours ago by Dialabrain.

Various choices are there in login options , but OP has asked how to delete the login in screen on start up that is very much impractical , secondly is using bypass the login screen .

I think you and me both know that when the OP said he wanted to delete the login in screen, they did not actually mean delete. We all know they meant to have the mac automatically login.