The following simulates removing a colorcast by converting to LAB mode and then using curves on the AB channels. However, you can use this method without leaving the original color mode.
It’s another quick-and-dirty method for removing a colorcast. After opening the document, take the following steps:

1. Select the Eyedropper tool and set its options to Size Sample 3 by 3 Average.

2. Drag the Eyedropper tool over the color you want to remove.

3. Make a new layer and fill it with the color that you just sampled (Edit>Fill>Use: Foreground Color).

4. Choose Image➜Adjustments➜Invert, or use the keyboard shortcut of Ctrl+I(Windows),Ô+I (Mac OS).

5. Change the layer’s blend mode to Color.

6. Lower the opacity of the layer to 50%.
That should get you into the ballpark. At step 2, you can also try duplicating the image layer, running the Blur➜Average filter and inverting the layer.

TIP: Where appropriate, try to set neutral end points first by using the eyedroppers in Curves or Levels.