I just bought one myself and found it kind of difficult to hold upside down while getting the plant out without bending the leaves/stems. I also tried pulling out by holding onto the stems and pulling up.

I think the easiest way, would be to take scissors and cut straight down the side of the plastic tube toward the bottom....and then pull it open. Or...cut down and then around. Your choice. But keep in mind obviously, that this will probably make it difficult to reuse the container it came in (depending on how you cut it.)