Method 1:
Put a flat blade screwdriver in the "U" of the clip and place the battery tube on the edge of a counter with the clip and portion of the tube hanging over the edge. With a hammer or mallet, hit the screwdriver while holding the tube firmly on the counter.
Method 2:
Clamp the top level of the clip in a vise with the tube above and hanging out past the vise. Place a block of wood against the lip of the tube, above the clip and give the block of wood a hit with a mallet or hammer.
EDIT:
Method 3: (works if the clip isn't too tight)
Put some cordage or a shoe string in the "U" of the clip and pull while holding the battery tube.
- Don