Your $file variable contains the name of the output file, so that when you do:

unlink ($file);
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you actually delete the output file instead of deleting the input file.

Otherwise, don't worry too much about the "uninitialized" warnings you get (in your screen shot), they are most probably due to an empty line at the end of your input file, so that the $sMonth, $sDate, $sTime variables don't get populated for that empty line. Just add a line like this:

next unless defined $sMonth;
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after the split (just after line 14), and this should suppress these warnings.