Compromised account

Hello, 

I recently received a text to my phone from outlook saying that an account that I had in the past was compromised. Of course, for security reasons, it only shows the first two letters of the username of that account. I have since forgotten about that account and the username and password that I used for it, so there is no way that I can access it. Is there away that the account can be deleted if all I have is my phone number? I have three accounts associated with the phone number. Two I still use, but the third is gone in the cloud. Someone clearly has the access information and I'm nervous that they have even more now. 

Thanks for the help!