No, you can't exclude a module. However, you can export a module package (to save a copy of it) and then delete it from your model. If you find you need the module again, you can import the saved module package.
Hope that helps,
'Exclude from project' works only on file level. This is a lot of work.
This approach is faster: Export the module and then import the same exported module. Then on project level import the same module with the 'Import Module package' command. Then use the option 'Adds as a new module' and rename it like 'NotInUse'. Then delete the original module and fix the errors who refer to the original module.
Thanks a lot Mike and Ruud!