function removeAlpha () {
  this.options.removeAlpha = true;
  return this;
}
Remove alpha channels, if any. This is a no-op if the image does not have an alpha channel.

See also {@link /api-operation#flatten|flatten}.

@example
sharp('rgba.png')
  .removeAlpha()
  .toFile('rgb.png', function(err, info) {
    // rgb.png is a 3 channel image without an alpha channel
  });

@returns {Sharp}