If I have, say, the string,
txt = "now is the time for all (good) men"
then I want to remove the substring beginning with "for" and ending at the end of the string, namely, remove:
subtext = "for all (good) men"
I do realize that an expression of the form
StringReplace[txt, regex ->""] or
will do it, but I don't know what regular expression or pattern to use.
The part of the substring to be omitted definitely begins with the specific text "for", but anything could follow it.