Can I set the default simulator for new projects in Xcode 7.1 or latest?

You can select the desired simulator via the Hardware > Device > [OS] menu (Xcode 9):

image While unchecking "Show as run destination" hides the simulator, this will also change the default value.

Updated image for Xcode 11.5 image

No need to delete simulators!

  1. Product → Destination → Add Additional Simulators...

Click on "Add Additional Simulators"

  1. In the sidebar, select the simulator you want to hide

List of iOS simulators

  1. Uncheck "Show as run destination"

New "Show as run destination" checkbox

Edit: Updated for Xcode 10