Source location in PHP to edit

Dear admin, I use network theme for single site, can you help me for these ….

1) how can I remove / hide the green Join Now button?

2) how can I remove / hide the login form near to ‘Pencarian untuk’ ?

3) How can I edit WPMU DEV – The WordPress ExpertsCopyright ©2012 BlogMokoGo back to top ? at the footer section ?

Thank for your help…