Well, here is the simplest and most un-recommended way ever: if I'm not mistaken, there will probably just be a folder in the Next War folder that has the new bomber graphics (under Assets/Art/Units). If you delete this folder or rename it, it should revert automatically.
Now, the good way to do it is to copy the Next War mod into your Custom Assets folder, rename it "Next War 2" or whatever you want to call your own little version of Next War, and then delete the extra art files. Then, load your custom version...that way, if you mess it up, then you still have the original unaltered copy! Call it an insurance policy for new modders.
Also, you probably will need to check the button graphics for either option above, because it probably refers to the Next War Atlas. Open up the "Art Defines Unit" *.xml (I forget it's exact name, but it's close to what I listed there) under the Assets/XML/Art file for both the Next War mod and the normal BtS game (in the Program Files). Search for the entry for the bomber, and make sure the button in the Next War version of this file is the same as it is for the BtS version of this file. If not, copy-paste, then save! And that's it.
