My Samsung Galaxy S3 had several homescreens initially that I want to delete. Just minimize one homescreen with the well-known zoom motion: Put your thumb on the left bottom corner of the display and the middle finger to the top right corner and move both finger into the middle of the screen. You get an overview of all homescreens.
To delete one homescreen choose one, move it to the basket icon and drop it. Use the +Icon to add a new homescreen.