How Do I Push a Local Git Branch to Master Branch in the Remote?

As people mentioned in the comments you probably don't want to do that... The answer from mipadi is absolutely correct if you know what you're doing.

I would say:

git checkout master
git pull               # to update the state to the latest remote master state
git merge develop      # to bring changes to local master from your develop branch
git push origin master # push current HEAD to remote master branch

you can install the git tool and it can help with merging branch to master. I created a branch in RStudio, worked on it, pushed changes to github. Then when I wanted to merge I opened this git GUI tool, navigated to the folder with my repository, then merged the branch to master. I opened RStudio to check if the changes had happened, then pushed to github from RStudio.

You can also do it this way to reference the previous branch implicitly:

git checkout mainline
git pull
git merge -
git push

As an extend to @Eugene's answer another version which will work to push code from local repo to master/develop branch .

Switch to branch ‘master’:

$ git checkout master

Merge from local repo to master:

$ git merge --no-ff FEATURE/<branch_Name>

Push to master:

$ git push