This document includes:

how to update remix.ethereum.org.
how to update remix-alpha.ethereum.org.
how to release remix IDE.

remix IDE release

git fetch origin master
git checkout origin/master
git checkout -b bumpVersion
update package.json version
remove package-lock/json version and generate a new one with npm install
merge PR
git fetch origin master
git checkout origin/master
git tag v(version-number)
git push --tags
github-changes -o ethereum -r remix-ide -a --only-pulls --use-commit-body --only-merges --between-tags previous_version...next_version
publish a release in github using the changelog
rm -rf node_modules
npm install
remove all soljson.js files in root folder
npm run build
npm publish
after remix_live is updated, drop the zip (from the root folder of remix-live repo) to the release.

remix.ethereum.org update

This is not strictly speaking a release. Updating the remix site is done through the Travis build:

switch to the remix_live
git reset --hard -master-commit-hash-
git push -f origin remix_live

CircleCI will build automaticaly and remix.ethereum.org will be updated

remix-alpha.ethereum.org update

remix-alpha.ethereum.org is automaticaly updated every time commits are pushed to master