GNU screen updating or reinstalling
You could install brew and use it to install a more recent version with the command brew install screen. That will currently install version 4.3.1, which (as of writing) is almost the latest release (a new release of screen came out less than a week ago and isn't in brew yet). You will then be able to run it from /usr/local/bin/screen. You can create an alias to simplify that.

You could remove the installed version, but it could be silently replaced by Apple at some point when you install an update. And it's always a good idea to avoid making changes in the /usr/bin directory unless absolutely necessary.

You could install directly from the source, but that version might not include OS X specific patches. The brew Formula for screen does include at least one specific OS X patch.