How do I make street address not a required field?
First, find which profile is being used in your contribution page by going to Contributions/Manage Contribution Pages/Choose relevant Page and select Configure over on right hand side of screen/Include Profiles.  This page will show which Profile is being used.

Second go to Administer/Customize date and Screens/Profiles.  Find the relevant Profile title and select Fields on the right hand side. This page shows all the fields in use and whether they are required or not. In each field, hover over Yes or No and change them as you wish.

Hope this helps.