What Maarten mentiond and to rename the projectname in the modeler you can rename the mpr file with tortoise SVN:

see https://docs.mendix.com/refguide/version-control-scenarios#file-management-and-java-development for the correct version to download here: https://sourceforge.net/projects/tortoisesvn/files/1.7.15/Application/

cheers 🍻!

You can do it in the Mendix sprintr environment:

1. Go to https://sprintr.home.mendix.com

2. Go to your project

3. Go to Settings > General on the left side

4. Click on 'edit settings', now you can edit your project name