Dear edu g,
Mary is correct in saying about deleting code as that will only lead to maintainability issues - there are far better less sledge hammer solutions to this:
1. Use and set the 'My Moodle' page for users - http://docs.moodle.org/22/en/my/index - no code changes needed.
2. There is a function 'is_siteadmin()' with the $USER global - e.g. if (is_siteadmin($USER)) - I believe that it is not totally recommended and may not be supported in future, but it currently exists. It does have a replacement but I'd have to look that up. However, this should get you going.