Can I compile for armv7 only (iPhone)?

I want to reduce the size of my binary file and removing armv6 can do that. Also, we set our game to require OpenGL ES 2.0, and I believe all OpenGL ES 2.0 capable iOS devices can also run armv7. So it wouldn't hurt to remove armv6.

The Unity player settings only allow setting to either armv6 only, or both armv6 and armv7. Is there a way to make it compile in armv7 only? Thanks.

I believe you can do that directly on Xcode. Go to Project / Edit Project Settings / build tab, and Project / Edit Active Target ... / build tab and there's a drop down menu where you can select that option

Since Unity 3.2 you can select armv7 only.