All the above.. as well as Ctrl-T (transform), shift click handles and fit to frame... Erasure tool is good but keep in mind that it is a destructive tool... once you erase the pixels they are gone forever. I typically avoid it and prefer to create a mask, fill the mask with a background color (white in your case) and then just paint away the mask revealing your photo at the desired size..

That's the beauty of Photoshop... powerful, flexible and many ways to achieve the same results.
Good Luck!