...
- Go to Tools>>Remove Plugin from project file.
- Add the project and then select the plugin from the lower window under "Select plugins to be removed from the project file', see figure 3.
- Click "Save" to save the project.
- Remove the plugin from source plugin manager: Tools >> Plugin Manager >> uninstall "the plugin", click OK and restart Source when prompted. Now you should be able to load the project file to source without the plugin loaded.
These steps are This is currently only required for plugins:
...