If she is ready.... ..Take the bottle away. If she is physically capable of eating off a spoon or drinking from a cup, she will do so when hungry or thirsty enough. But then, be sure you really need to wean right now.
Substitute with cup. When it's time to wean the bottle one of the best strategies is to offer her favorite drink in a cup. To further stack the odds in favor of cup use, water down the milk being offered in the bottle, diluting its taste thus making the bottle less attractive. Another more aggressive strategy is cutting off a portion of the nipple each day, literally transforming the bottle into a "sippy cup".