Hi @Elena_GabrielaSi,
Thank you for your question! Currently, if a user has permission to create a project, the "Import MS Project" option will be visible to them. There isn't a way to split/toggle to hide/show it.
I also checked with our database team and there isn't a way to disable that functionality besides removing the permission to create projects altogether. I would recommend submitting a feature idea on our Innovation Lab HERE.
- Monica