To remove the existing wristband, please put a pin in the small hole where the watch case connects to the existing band.
Push the pin into the hole as far as it would go then gently twist the strap off the case.
To avoid the internal spring pin from flying out, please place your finger over the edge as you're twisting the strap off.
When you have your Premium Silicone Quick-Release band on, you'll see that there's now a handy lever on the underside to allow you to easy slide the pin back to remove.