# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/-{9,}(?:(?!-{9}).)*?- \[\d+]//gm;t' <<< "---------Some text is here.---------More text is here - [3548]----- Even more text is here.-----------More text is here - [408]--------- Even more text is here again.
-----------------------More text; is here - [3548]"
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for SED, please visit: https://www.gnu.org/software/sed/manual/html_node/The-_0022s_0022-Command.html