Check existing remote:

git remote -v 
# origin <https://github.com/username/repo.git> (fetch)
# origin <https://github.com/usernam/repo.git> (push)

Change repository URL:

git remote set-url origin <https://github.com/username/repo2.git>
# Change the 'origin' remote's URL

Verify new remote URL:

git remote -v
# origin  <https://github.com/username/repo2.git> (fetch)
# origin  <https://github.com/username/repo2.git> (push)