4
What you need to do is goto System admin ¦ Groups, and setup the permissions you want for the anonymous group, giving them the access you want them to have. Once done, simply goto System admin ¦ Blocks managment, and hide the login block.
If you are using XOOPS 2.2.X you can also uninstall the profiles module and pm module from Modules ¦ Administration, if you are not going to be using them.