Can I change a 26" to a 24" tire on a Huntington Schinn Women's tire?
Your 26" tires sit on wheel rims, whose diameter is probably 559 mm. 24" tires will not fit onto these rims; to use 24" "junior" tires you actually need smaller wheels, of a 507 mm diameter. These smaller wheels require a different frame.

Smaller rims require a different frame mainly because hardware related to the wheel which is mounted to the larger frame is at the wrong location for the smaller wheel diameter: this hardware includes mounting bosses for rim brakes and fenders. Also, on smaller wheels, the existing pedals will have less ground clearance; you might strike the ground when pedaling through turns. 

(That's okay, because since for your height, you will probably benefit from shorter cranks anyway: see this crank length versus body height table on the Sugino website, according to which, a 152 cm person should consider pedal crank arms of 155-160mm.)

Luckily, your Schwinn Huntington Cruiser itself comes in a girls' size with 24" wheels. If the Schwinn Huntington Cruiser is your dream bike, all you have to do is exchange the adult 26" one for the youth 24" and you're set.

Though I strongly suspect you would be comfortable on the 24" version of the bike, is that really necessary? Smaller wheels will not help with balancing; that is, not with balancing the bicycle while in motion. I suspect that what you mean by balancing is that, while seated, you have trouble reaching the ground. However, this is okay; shorter people should not expect to be able to reach the ground from a bicycle seat.  For that matter, taller riders on a large bike should not either. If your feet can easily reach the ground while you're seated, it means your knee is too bent at the bottom of the pedal stroke, which means your seat is too low.

The proper bicycle technique is to get up out of the seat when you come to a stop and stand over the top tube, not over the seat. Then when you get moving again, get the bike in motion while briefly standing on the pedals, straddling the top tube. As soon as it is moving, get into the saddle. Your cruiser bike makes it easy to straddle the top tube because that top tube curves radically downward. This video demonstrates the techniques. Practice this starting and stopping technique until it is second nature, and you're not bothered by difficulty reaching the ground out of the seat.

A useful technique not shown in the video is to come to a stop to a raised object, such as a curb, where you can plant one foot without getting out of the saddle. When you start moving again, you give a good push with that foot, and push down on the opposite pedal with the other foot.

Even if you had the 24" version of the bike, you'd still want to adjust your seat so that you can barely touch the ground with extended toes out of the saddle, if at all.  I am 6'1" tall and actually used a 24" bike for quite some time! I used it for daily commuting, and even did a 200 km road trip with an overnight stay. Of course, I had to get an extra long seat tube for it. And, guess what, I could barely reach the ground with my toes from the saddle! That's what it takes for a proper fit. If the seat had been any lower, pedaling would have become inefficient. The leg has to be almost fully extended at the bottom of the pedal stroke. And since the bottom of the pedal stroke is still quite a ways from the ground due to the necessary ground clearance, that means the ground is hard to reach out of the saddle, regardless of how tall you are or what size bike you're trying to fit.