If draft-stop caulking was applied, then there is a simple solution. If silicone or thermal plastic caulking was used, then you will have a little work to do. Draft-stop caulking is designed to be put on in late autumn when keeping cold air out and warm air in becomes important. It can easily be removed the next spring. Simply peel it off as if it was masking tape. Silicone caulking can be removed with a special silicone caulking stripper. Thermal plastic caulking will have to be removed with a knife and elbow grease. This, of course, is a tough job. Another option is to keep the windows caulked shut and install a ventilation system above the window and through the wall. If the caulking was applied to stop any winter drafts, maybe it should stay. With a ventilation system installed, you could then control the amount of air movement in the summer and not worry about any drafts coming through the window in the winter.