Default ambience, can they be removed from land?

As with any property on Second Life, there's this accursed default ambience that is this depressing, solemn wind of barrenness. The problem is, it's an empty wind on a sim where the owners have no desire for the sound, or for that matter, the "wind" effect itself.

Is there a way for the owners to take control of the sim's settings, and control not just the environment editor's main settings for the sim, but also remove aspects such as wind and the default ambience so that no one who enters the sim has to endure them?

I don't think there's any way to turn off the wind entirely. The best you can do is mute it in your viewer, so you don't hear it. (Edit -> Preferences -> Audio & Video tab -> Volume section -> Ambient slider) Anyone else who wishes not to hear the wind will need to do the same thing themselves. There's no way to force it on others. Also note, this will mute footsteps as well.

I would question your use of the word "endure", by the way. Unless you've got a powerful subwoofer, you'll barely ever hear the wind. Most people on laptops aren't even aware the wind sound exists at all. Same goes for those with cheap desktop speakers. It takes a fairly decent speaker setup to make the wind well audible.

Actually, I should qualify that statement. If you're using a Realtek soundcard (standard issue with most nVidia motherboards these days), certain low frequencies, including some of those found in the the wind sound, can sometimes end up undesirably amplified. Occasionally they'll also stutter a bit, causing an annoying repetitive popping sound. To prevent both problems, disable Dolby emulation in the driver settings.