I did a search on this and all I found was to use ACE to take winglets off a particular model, but it does not work for me. I know there is a way to change the aircraft config file in CS 757-200, but not sure how. I want to get rid of the winglets on the UA 757. I have downloaded and installed ACE 1.4, but the program says it is 1.3, don't know if that is OK. I have the pro pack version.
Thanks,
Larry

open the aircraft config file and remove W that comes after the engine type on the model line. eg.  PWW or RRW for the texture that u want and save...hope that helps

look at here:
http://www.captainsim.org/yabb2/YaBB.pl?num=1224289649
it's explained how to add them, simply remove a "W", as rupesh said.
Bye!
Andrea

I'm sure you have your reasons, but winglets are a good thing.  They improve the efficiency of the aircraft by minimizing wingtip vortices.  You will burn less fuel to go the same distance at the same FL at the same weight and cruise speed.

Like Andrea's link points out, you can edit the manual config, but I've had no issue using ACE to add or remove them, if you use ACE correctly.  It can be confusing until you learn how it expects to be used, but once these config changes are made in ACE simply reload the plane and it will load with the correct model, winglets or not.

Hope it helps!  ;)