I have a github profile and I forked someone's repository into mine. and locally I have cloned this repository using
git clone https://github.com/my-github-page/repo-name
Now, since some time has passed the original repo owner has update his repo, but mine is behind. So, if I would like to do git pull to merge his changes into mine. But I would like to push my changes from local to mine. 
In simple terms, if I do git remote show origin I get this:
[root@localhost xxx]# git remote show origin
* remote origin
  Fetch URL: https://github.com/my-github-profile/xxx
  Push  URL: https://github.com/my-github-profile/xxx
  HEAD branch: master
  Remote branches:
    1.0          tracked
    master       tracked
    system_tests tracked
  Local branch configured for 'git pull':
    master merges with remote master
  Local ref configured for 'git push':
    master pushes to master (up to date)
Now I want to change the FETCH URL to the original src of the repo. Because the original is updated but my fork is behind
 
     
     
    