[boost] Stale branch removal - safe?

There are some stale branches (over 7 years old) from the svn conversion in the Boost.Uuid (and other) repository: https://github.com/boostorg/uuid/branches/stale Is it safe to remove these? example name: svn-branches/units/autoprefix Apart from "master" and "develop" branches and all the version tags, is anything else sacred for branches or tags? Thanks, Jim