I’ve had Skype on my computer for years, predating when it was acquired by MS. My Skype account was also not linked to an MS address but a Gmail address. That said, it is possible that I was forced into an MS account by keeping Skype. Skype was discontinued earlier this year, though. And I uninstalled it.
It is unclear to me if I currently have an MS account, but I don’t think I do.
What matters most is whether your OS actually uses that account or not. You can run a local account on your machine, while still having a Microsoft account, that you only access in a web browser for example.
In your Windows settings, you can check whether your account is connected or not. While you’re still on 10, you can also choose to disconnect and use a local account instead. Then, you can uncheck some options to prevent Windows from connecting you again, or better yet : from ever asking you to connect again.
My Windows isn’t in English, so adding screenshots wouldn’t help, but I can guide you through it in more details if you need it.