I'm sure
Login to Mysky and go to My Details.
Scroll down and look for Additional Users -make a note of unidentified users and remove them.
If they reappear then someone has access to either your ownSkyID or other secondary logins that may already exist
eg on my own account I have 2 extra logins available which are a throwback to when you could have up to 5 additional email accounts (pre 2016?) .As a result my wife's email account login means she is also an Additional User - my son's old email account is still active (I use it as a backup email address) and also appears as an Additional User.
These addional email logins (sky.com accounts) are no longer available.
I hope I haven't confused you ?