Vacuum breaker cap - how to remove it??

Hi. New to the forum so I apologize if this seems like too simple a question.
How does one remove the vacuum breaker cap on a Mansfield 500 series unit? I've read that some say just pry it off with a screwdriver but prying on cold plastic with a screwdriver sounds a little iffy to me. I just replaced the internal parts on the rod with their kit #630-7755 but it still leaks badly from the cap area. Thanks for any expertise on this!

They just pry off.

Well, I got the cap off as gently as I could but the plastic bonnet cracked in the process. It didn't matter in the end as the valve washer was completely rotten anyway. Bought and installed a new bonnet and valve and to my surprise....when turned on, water pools up on top of the bonnet ( I have the cap removed so I can see this) and drips off. I don't understand - I was expecting to have a nice leak-free fix at that point. What gives?!

What's a new vacuum breaker worth? I'm wondering why you put yourself through all of this grief if it could simply be screwed out and replaced.

I only bought the kit ($3) after I removed the original and saw that the washer was rotten. Really, very simple and no grief at all....just that it isn't working right is the thorn in my side.
So, any pros out there that can explain why water can still pool up out of the anti-syphon bonnet?? FYI, this is on my faucet in the garage so I am aiming for no leaks at all.