# If you'd like to omit non-matching lines from the result; add ';d' to the end of the expression.
sed -E 's/^IT [0-9]{1,5}\\/(?:19|20)\d{2}\((?:MN|[HB-EGKMUNLSTV])\)/ /gm;t' <<< "IT 1/2014(G)
or
IT 1/2014(MN)"
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