This may work (UNTESTED):

my @files  = (
    $rrconfig::locodata,
    $rrconfig::availlocodata,
    # add other file names here
    );

{
    local @ARGV = @files;
    local $^I = '.back';
    # change '.back' to '' if your system supports it

    while ( <> ) {
        next if /^[^:]*:$delroad:$delnumber:/;
        print;
        }
    }
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