Username & Password Router

I work for a company, and am new, like five weeks new to this business. One of the employees left two weeks after I got here for personal reasons, and the other one was fired for being a herio... he did bad stuff.

Anyways, our Director of IT is new as well, and I want to figure this out because he doesn't know the resolution either. If I plug my computer directly into the router, how can I go about changing the wifi password?

I know to use the Default Gateway, which leads me to a Dell Switch, which is weird because we have Cisco Routers, but we don't have knowledge of the username or password to this page, and the only one that did was the addic.... guy that got fired.

There should be a way to access and change this information if you plug directly into the router, correct? If not he has suggested reaching out to Cisco, or our Dell rep, but being new, and the only IT person here, I think it would look a lot better if I found the resolution to this instead.

Any help would be appreciated.

Thanks, friends.