! [rejected] refs/pull/48/head -> remove-bootstrap (non-fast-forward) exit status 1 code example

Example: rejected master -> master (non-fast-forward)

# if you updated your files on github.com so may be thats its asking first pull
# request then your push the request.
# so Very simple first:
# not use -f 
git pull origin master
# then
git push origin master