How to Make Evil Childproof Caps Easy to Open
The web link shows several different hacks for child resistant caps if you want to lock them down.
For getting the cap off the first time, I use either channel-lock or regular slip joint pliers to grip and turn the cap to open it for the first time. You want to squish the outer ring on the cap, but not crush the bottle top.
After it is off, you can do one of the hacks, switch to a known good cap, or switch to a known good bottle. I've had a few favorite flavors come with a wonky bottle cap, so if you already have an empty in the same flavor, you don't have to worry about cross contamination with the old/new
juice flavor. If you don't mind using the pliers, you can also just keep using them until the bottle is empty.