Remove Log-in from homepage of themes

I am trying to make as many of the themes available as possible to customers including the buddypress themes. It seems that for most of them this is easy to do. The one component that I find I want to remove from a theme is the log-in element from the front page. On some themes there is an option under appearance to remove the log in (put this on all themes I request). On others, removing the profile.php file or a few lines somewhere seems to do the trick.

However, there are three themes I haven't been able to remove the log in from. (Or if I have I cannot remove the css elment which creates the space the login box appears in.) So,

how can I remove the log in from the homepage of Corporate theme, Community theme and Network theme?