Once you have the other fasteners all unhooked the top should slide off toward the rear of the car. The bar you are talking about likely (if original) goes the almost then entire way accross the back of the top, but is secured only on two chrome clips. Sometimes it is necessary to wiggle the entire top from side to side. I have also had to press down in the middle to loosen up a top that has been in place for a long while. If all of this fails, get out a can of WD40 with a little red pastic tube and spray into the meeting sufaces LIGHTLY...and be sure to get the runs cleaned up ASAP with a light detergent.
Only once in many years did I actally have to resort to my final idea...it was a buddy's Sunbeam Alpine with a hardtop. We WD40'd the heck out it and got a small dowell under the seal and TAPPED the dowell and top off the clip.
Be very careful, making sure you have the dowell centered on the bar if you have to resort to this.
You can access the bolt to the clip from underneath, but the clip has to be angled to lift out...very difficult to do when the top is still attached, but might work. (?)
GOOD LUCK and have at it.
Bruce