git push is pushing to the wrong repo

Question

After recently taking a programming course online which required us to upload our homework assignments into Github, ever since then whenever I type git push -u origin master I get:

remote: Permission to my-github-username/mygithubrepo.git denied to rheros.
fatal: unable to access 'https://github.com/my-github-username/mygithubrepo.git/': The requested URL returned error: 403

rheros is the name of the repository that I used to push my homework assignments to. Obviously, now I'm not using rheros anymore, yet the command line thinks I'm still trying to push to it. I tried checking whether I have a faulty SSH key, but everything looks fine.

How can I make my command line effectively forget about the existence of a completely irrelevant directory that I pushed to before?

EDIT git remote --verbose gives:

origin  https://github.com/my-github-username/mygithubrepo.git (fetch)
origin  https://github.com/my-github-username/mygithubrepo.git (push)

So far, none of the suggestions below have helped me: it seems that the rheros repo is running somewhere in the background of my command line, and I can't figure out how to eliminate it.

Answer 1

First check what the current git repository is, if any using:

git remote -v

Then, confirm your new repository exists by checking the github website and copying the right repository url

Overwrite the repository url by running:

git remote add origin https://github.com/my-github-username/mygithubrepo.git

Try git push again:

git push origin master

Answer 2

git remote remove origin https://github.com/my-github-username/mygithubrepo.git

After this, you can add the repository you want to push to normally