u can't hide the password option on the sign in screen
of course you can no idea why you would say this?
To remove the password login part what you need to do is
Open a run box ( Windows key + R )
Type in netplwiz
a box will come up at the top of it will say " Users must enter a user name and password to use this computer " Un tick that box and press apply. When you do this you will be prompted to add your current password required to log into the account put it in and restart. Walla no more password needed.