In Xcode after cloning :
--Source control navigator (cmd-2)
--Expand top folder tree
--Expand Remotes folder
--Right click on the remote origin you want to delete -> delete

To add a new remote origin :
--Right click on the remotes FOLDER
--Select "New your-project-name remote"
--Fill out the options, make sure your github account is selected.
--Double check on your github page to make sure it got created.
--Profit??