If he is taking the bottle to bed with him, that needs to stop immediately. It's wretched for his teeth. If this is the problem, he needs another thing that will soothe him as his cup does--a blanket or stuffed toy is a good option. If he picks it out himself at the store, he may be more apt to use it, but make sure he is aware from the get-go that the new stuffie or blanket means no more bottle. Make sure he knows that when you buy that thing, the bottle is going away for good.
If he is drinking the bottle before going to bed, you need to replace a night-time drink with a quick sip of water from a sippie cup. He doesn't require those extra calories before bed, and is only using the bottle to soothe himself and calm down for sleep. Try starting a new bed time routine that does not include bottle time--a bath and reading a book is a good option. Make sure, again, that he is aware that reading a book at night is replacing drinking the bottle. Let him pick out a couple of books at the store that you can read to him.
Good luck. If you must, take it away and say that's it. He will fight it, but if you are consistent, it will be alright. If you know anyone that has had a baby recently, you could maybe talk your son into "giving" the new baby the bottles because he's a big boy and doesn't need them anymore. Or, you can leave them out on a table for the "bottle fairy", and the bottle fairy can leave him something special in return (a stuffed toy or blanket). Or, just see what he thinks about being a big boy and throwing them away. If you get him excited about being a big boy, and he understands that big boys don't use bottles, it may help him let go.