Taken from https://stackoverflow.com/a/24762313/1947087
git tag -d <tagname>
git checkout <new commit or branch>
git tag -a <tagname>
git push <remotename> <tagname> -f
for example:
git checkout 2.0
git tag -d v2.0
git tag -a v2.0 -m"Version 2.0"
git push origin v2.0 -f