I use Notepad++ and I need to delete all lines starting with, say \"abc\".
Attention, I don\'t need to replace the line starting with \"abc\" with a empty line, but
Try replace
^abc.*(\r?\n)?
with
nothing
The ^ indicates the start of a line.
^
The . means wild-card.
.
The .* means zero or more wild-cards.
.*
x? means x is optional.
x?
x
The \r?\n covers both \r\n (generally Windows) and \n (generally Unix), but must be optional to cover the last line.
\r?\n
\r\n
\n