I'm assuming that you don't currently work for the company? If not, you first have to get hired by the company as a Professional Bather. After your initial 90 days, you are eligible to be considered for a spot in a grooming academy. This process can take up to a year because of your progress as a bather, your store's need for another groomer, and when/where academies are going on.
There isn't just one grooming academy. Salon managers become academy trainers after going through a lot of intense training. So wherever there is a certified academy trainer is where grooming school/academy can go on. In your area, since you mentioned Canton (I used to work in that district)... the only stores that offer academy training are Medina, Parma (maybe), Cuyahoga Falls, North Olmstead (maybe), Macedonia (maybe), and Elyria (maybe).
The only ones that I know for sure are Medina and Cuyahog Falls, because as managers change so does where academies are offered. I worked at the Medina store but did my 4-week grooming academy at the Canton store. So, to answer your main question... no, you do not have to be hired at a store that offers grooming academies.
Grooming academy is no longer offered at the Canton store. The salon manager from Canton is now at Cuyahoga Falls. But if you're closer to Canton, or wherever... get in there first, then work towards academy.
I hope that helped?