Hi and welcome.
The top is probably binding on the safety bar. Try raising the top off the bar before you pull the release lanyard.
I suspect these terms may not mean anything to you, so look through the forum to familiarize yourself with the features of HiLos and you may have success. Your problem description was sort of vague, let us know what you have tried to get it to lower.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH, Progressive Dynamics Converter, Fan-Tastic Fan
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew