remove lines/contents that matches a pattern in Linux

I want to remove all lines and contents in comments i.e. "--" from a file. For example my data is

---------
--Text1
--Text2
---------
Text3 --Text4
Text5

and my output should be

Text3
Text5

I tried sed '/^--/d' test.txt and it removed all lines that starts with -- but I want to remove all contents after -- as well like line 5 above.

Solution

Use this Perl one-liner:

$ echo 'foo--bar' | perl -pe 's/--.*//' 
foo

The Perl one-liner uses these command line flags:
-e : Tells Perl to look for code in-line, instead of in a file.
-p : Loop over the input one line at a time, assigning it to $_ by default. Add print $_ after each loop iteration.

s/--.*// : Replace literal -- followed by any character repeated 0 or more times with nothing (= delete comments).