Normally, the cap tab must align with the gap in the ring around the neck of the bottle. I remove the tab to this alignment is not needed and the cap can be removed in any orientation.
Locate the inside tab, opposite the thumb tab on the outside of the cap. Highlighted in red in the second picture. Carefully slice it away using a box cutter, utility knife or razor blade. Just keep removing material until the cap will pop off in any orientation.