DO NOT TOP!!!!!! i have the same prob bro, but its to late for that. youll lose significant yield. try tying them down or lst as some would call it. check out my grow and see how i tied mine.
it's a kind of a debated topic... most people only top up until the last week or two before flowering and some people say it's ok to top the week of flowering but generally not any later than that. best bet at this point is probably to try to stake or cage the plant and try to tie it down