Thank you for the responce, but it is not what I requested. I want the location of the "account Default Pictures" so I can delete them. Then the "standard" user will not be able to change the login picture.
Motive:The picture will remain my logo.
%allusersprofile%\Application Data\Microsoft\User Account Pictures
Type the above in Start-Run dialog. Note that the following folder holds all the default picture files in the folder %allusersprofile%\Application Data\Microsoft\User Account Pictures\Default Pictures