The only ones I could find in stock when I bought my first set were the ones equivalent to 110psi. These are still the only ones I can find in 700x23c with UK stockists, so even if you wanted to go softer, you might struggle.
I think it IS technically possible to remove them without cutting them off. However, I think you'd need to go to a proper fitter for them to do it on their jig (Tannus have manufactured a large 'machine' for bike shops to fit/remove them with relative ease).
That said, I put mine on in the knowledge that I fully intended to keep them on for their lifetime, so will just hack them off when they reach the end of their working life.