There is probably caulk right down the centre of the underside of the track.
This track probably isn't going to be easy to remove. Avoid using metal
tools if you can as scratching the tub is all too easy. I had some hardwood
wedges that is gradually worked under the track at one end and eventually
had the track wedged up enough to start working down the length of the
A package of door framing wedges from your local building supply might do
I found it to be a labour intensive job.