Right-click on the game in your Steam library and select "Properties" Then Now click this You are in the game folder! Now go into Contraptions scroll down, and find the save folder you're having problems with, then click it. Now if you have Notepad or Notepad Plus, right-click the JSON file and edit it with either one. Now your page should look like the photo, however, I am using Notepad + for this one so it may look different from yours.

Now here's where we remove the mod from the save! Now let us say this mod is the mod you want to get rid of. ,{"Name":"QuickRightClickOptions","WorkshopId":"2516131949","UniqueIdentity":"Pump3d-Quick Right Click Options-2516131949","HasWorkshopId":true} So all you have to do is delete this part from the JSON file with the period in front of it and that should get rid of the mod out of your save! Also, make sure that the periods are lined up with the other mods from when before you edited the JSON so nothing breaks.

I hope your problem was fixed, thank you for your time! The steps provided in this guide are for informational purposes only. The author is not responsible for any unintended consequences, including but not limited to loss of game data, corruption of save files, or issues with game functionality. Modifying or removing mods may affect your game, and it is advised to back up your files before proceeding. Use these instructions at your own risk. Always comply with the game’s End User License Agreement (EULA) and Steam’s terms of service.