Transfer of administration

I have been "persuaded" to take on responsibility for the website of a local charity. I have corporate IT experience and had a systems admin/DBA role 15 years ago, but I'm a bit out of touch.

The website was hosted on namecheap at domain b-d.org, and was created by someone I don't know, but can contact. The charity has purchased domain bd.org, which is it's preferred name, and this is hosted at 123. I have access to all the admin at 123. The original creator gave me a key to import the website, which I have done and it is all working nicely BUT the "owner" of the database still seems to be the creator e.g. 123 logs me in as them by default. How can I change the owner to me (without breaking the website, obviously)?