Yes, you can still LST it but you'll have to do it slowly. Tie it off near the top and pull it over a bit until you feel resistance, then stop and tie it off. Then every day tighten it up a bit. If you try and pull it too much in the beginning you could break the stem. So a little bit every day.
I think part of the problem is that your lights were too high above the plants and they stretched while reaching for the light. New grow keep the lights closer to the plant and raise or lower them to keep your node spacing at about 1".