Your best bet would be to go to Steamapps/Common/Railworks/content. Be sure that you've identified the correct code for the route (generally a lengthy array of letters and numbers without spaces). Will show up in the game when you click on build on the initial screen on the right hand side near the bottom.
Now that you've done this, right click the content folder (be sure you're connected to the internet first), and look for the 'previous versions' selection. If this brings up a copy of the content folder of the route from before you made your error, then you may be in luck. Delete the faulty route from the current content folder, and replace it with the one from before your mistake.
Be sure to re-enable any providers that you've unticked the fly out menu in the editor as well, so that you can be sure that all the assets are loaded prior to resuming what you've done.
And last of all, be sure to backup anything before you edit it to avoid repeats of this kind of situation!