public void removeTarget(NodeType nodeType) {
        require(nodeType);
        writeChange((change) -> {
            Version target = Optional.ofNullable(change.targets().get(nodeType))
                                     .map(OsVersionTarget::version)
                                     .orElse(Version.emptyVersion);
            chooseUpgrader(nodeType, Optional.of(target)).disableUpgrade(nodeType);
            return change.withoutTarget(nodeType);
        });
    }
Remove OS target for given node type. Nodes of this type will stop receiving wanted OS version in their
node object.
node-repository/src/main/java/com/yahoo/vespa/hosted/provision/os/OsVersions.java