I know this is a dead thread but just to help anyone else interested by the thread title.

With speed controllers (I'm using some Botbitz ESCheap85's btw) it's not necessary to 'cut' the red wire as such. You can simply use a small flat headed screwdriver and lift up a small piece of plastic on the RC connector which holds the wire in place. Simply pull out the wire gently whilst simultaneously holding the plastic tab up. This way it's easy to just push it back into place again too.

Dan ^_^