git add upstream https://github.com/harshraj22/Practice_plan.git
(add upstream branch, as you created local git repo now, it isn't expected to have an upstream)
git fetch upstream
(fetch all changes from upstream to local repo)
git rebase upstream/master
(rebase your current branch from master of upstream, you can also use git merge --allow-unrelated-histories upstream/master
if you prefer merge commit)
git remote rm origin