Apologies for the confusion.
You haven't taken over anybody else's account. What's happened is that, during onboarding, you elected to connect a Facebook account and we pulled the logo, profile picture, banner, and description from that business account.
Every part of your profile, including your profile picture, is fully editable. If you need a tutorial on how to edit, see this link:
If you need any further help, please reach out to your Community Manager via the link below: