One can't actually move a remote branch, but you can copy a branch and delete a branch, so...

Copy oldbranch in repo to newbranch.

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git push {repo} {oldbranch}:heads/{newbranch}

Ex: git push origin foobranch:barbranch~ renames ~foobranch to barbranch

Remove a remote branch: it’s all about the colon!

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git push <remote_repo> :heads/<branch>

Example: git push origin :heads/some-branch removes some-branch from the remote repo (apparently git push origin :some-branch works as well).

This works for removing a tag as well:

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git push origin :sometag