The best would probably be considered to be
s/^\[[^\]]*\]//g
which says take a [, as many non ['s as possible and a ] and
get rid of them. The dot is slightly often misused in
regexen and you should try not to get the habit of
using it where another construct is more suitable otherwise you may be bitten later on. I suggest you
read at least Death to Dot Star! and the replies to it for some
more background.