Git

git clone --branch <BRANCH> <URL> <LOCAL_FOLDER_PATH>

git remote show origin 
OR
git remote -v

git remote set-url origin <ORIGIN_REPO>
The ORIGIN_REPO is the url for your forked repository

git remote add upstream <UPSTREAM_REPO>
The UPSTREAM_REPO is the repo from where you forked your repository

git fetch upstream <BRANCH>
git merge <upstream/BRANCH>

git add .
git commit -m "message"
git push 

Make sure you've pulled the new upstream branch into your local repo:
    First, ensure your working tree is clean (commit/stash/revert any changes)
    Then, git fetch upstream to retrieve the new upstream branch

Create and switch to a local version of the new upstream branch (newbranch):
    git checkout -b newbranch upstream/newbranch

When you're ready to push the new branch to origin:

git fetch upstream <NEWBRANCH>

git checkout -b <NEWBRANCH> upstream/<NEWBRANCH>

git push -u origin <NEWBRANCH>

git branch 
  
in case you want to change to another branch 

git checkout <ANOTHER_BRANCH

git clone https://github.com/<USERNAME>/<REPO> 

Example: 
git clone https://github.com/amitsaran/amitsaran.github.io.git

Source:
https://superuser.com/questions/557903/clone-github-repository-without-account