Phone compromised by unauthorized hotmail account.

https://opm.myidcare.com/cyberscan reports that my phone number was compromised by a hotmail account that I did not create.  It appears that hotmail is commingled with other Microsoft services and deletion of the hotmail account, assuming it can be done, may have undesirable consequences.  What are the relationships, how could the account be created without my knowledge, and how can I delete just the hotmail email without compromising anything else?