What is the Regular Expression to find the strings starting with [ and ending with ]. Between [ and] all kind of character are fine.
[ and ] are special characters in regular expressions, so you need to escape them. This should work for you:
\[.*?\]
.*? does non-greedy matching of any character. The non-greedy aspect assures that you will match [abc] instead of [abc]def]. Add a leading ^ and trailing $ if you want to match the entire string, e.g. no match at all in abc[def]ghi.