one of our horses had so many wingalls his fetlock looked twice the size it should, never gave him any trouble so we never did anything to them. worked well for all concerned. I'd let them roam as much a possible, slow movement of grazing helps lots of things
Out as much as possible I think. Mine has windgalls permanently, never caused a problem so far (touch wood!), but I do make sure to boot him up well for schooling etc. for support and cold hose his legs after riding. He's turned out 24/7 too. His windgalls are always up during the summer and go down over the winter.
You really need to find out why your horse has developed windgalls as they only come up to protect a strain or injury - often to a ligament. If the horse is moving around it allows the windgalls to stay quite squidgy which causes less discomfort.
Windgalls are usually found in the heavier type of horse and it is worth investigating why they have suddenly appeared. They are a distension of the synovium/joint capsule in the feltlock, usually they are an indication of a slight strain.
My horse has them, they are less when out in the field, worse when he is stabled. I have found stable bandages particularly the magnetic ones to be very helpful. Hard ground can also make them worse too.