oh-my-fish/plugins/jump/unmark.fish

function unmark
    if test (count $argv) -eq 0
        echo "Usage: unmark <MARK_NAME>..."
    else
        for mark_name in $argv
            if test -d $MARKPATH/$mark_name -a -L $MARKPATH/$mark_name
                command rm -i $MARKPATH/$mark_name
            else
                echo "No such mark: $mark_name"
            end
        end
    end
end