Only way would be through XML editing. It's pretty simple to just edit the mod's files.
Mods are stored at this location, or something similar.
C:\Program Files (x86)\Steam\userdata\<YourSteamID>\205990\local\mods
Go there and locate your mod, look for a folder that looks something like this, but with different numbers. If you've made multiple mods, there will be multiple folders. Use the dates on them to find out which one is the mod you're looking for.
m76561197976421844_1397232480
Open your mod's folder and use this tool to convert the data.xr to xml.
http://steamcommunity.com/workshop/discussions/-1/558756256352912366/?appid=205990
Open the xml file in your favorite text editor. Locate the items you want to remove, delete them. Be careful not to delete anything else, only the things you want to remove. And make sure to delete all of the item, can't imagine what would happen if you leave half of one in there, but it wouldn't be good. Make back-ups just in case.
If you have any questions, feel free to ask. I'll be glad to answer.