You are getting this error because “origin” is not available. “origin” is a convention not part of the command. “origin” is the local name of the remote repository.
For example you could also write:
git remote add myorigin git@github.com:myname/oldrep.git
git remote add testtest git@github.com:myname/oldrep.git
See the manual:
http://www.kernel.org/pub/software/scm/git/docs/git-remote.html
To remove a remote repository you enter:
git remote rm origin
Again “origin” is the name of the remote repository if you want to
remove the “upstream” remote:
git remote rm upstream