'Reset Apple ID' - receiving an email addressed to someone else?

My name is Kahli Hong, my dad's name is Sung Hong. I keep receiving emails addressing 'Sung Hong' to reset my password (Sung Hong's password). How can I unlink our accounts? I did not believe they were truly linked via emails to begin with...

There is no link in the email to simply say 'this is not me'... I'm still able to change Sung's Apple ID Password through this email, which concerns me.

Kind regards,

Kahli Hong