The menu options/button labels are slightly different in other programs, but I did it in Gimp so that's what I'll use for the instructions. 🙂
Click on the Colors menu, then select the Levels option. in the Color Levels window, there are three eyedropper buttons next to the "Auto" button. Click on the far right one to tell the program you're setting a white point. Then, in the photo look for something that should be white and click on it with the point of the eydropper. If the photo doesn't look quite right, keep moving the white point around by clicking on other white items until the whites look the way they should. From there, you can adjust the levels of the other colors as needed. All I did with your photo is the white point since it looks OK to me after that. Of course, a more accurate way is to use the color temperature slider in Photoshop or Lightroom, but this is the easiest way I know of for a quick fix.
