I swapped Grace's bottle for a sippy cup when she was about 14 months old with no problems.

At 23 months your daughter doesn't need a bottle, but that doesn't mean that she shouldn't have one. It's up to you - if you don't mind her having a bottle then that's fine, but if you would prefer her to drink from a cup then start to introduce that more and see how you go. You could maybe swap one of her bottles for a cup and then introduce the whole cup thing slowly over time. To me, it's like dummies - Grace still has one at nearly two. She doesn't need it, but she likes it and it doesn't bother me so for now she can have it.