I actually quite understand your position and how you feel about that. Anyway, it would be quite hard for you to remove the brand name on your sunglasses if the logo is prominent, so may I remind you that you perhaps should try to put some paper like something on the brand name to hide it. Actually, you could also get another pair from an online shop which have no brand names.
Firstly, check the brand name carefully. It is likely to be just a piece of thin membrane. Usually, producers are not gonna stick a brand name on the glass because it will definitely affect the view of glasses. You can easily tear the membrane off. Then, if there is really a sticky brand name on your glass, you can soak your glasses into the water. The glue will be softened, so it will be easy for you to remove the brand name. Finally, if it doesn't work with the help of these two tips, you can go back to the store and ask the seller to remove the brand name for you. Thus if there is any damage to your glasses, he will cover the expense.
I was once in the same kind of problem,the brand name on sunglasses looks very uncomfortable. But don't worry, there have two ways to deal with the problem. The first method,use hair drier to blow the brand,you could easy remove it while the glue melting. The second method, soak it in the hot water for about 5 minutes and use lube oil to remove it. There will be no any scratches on your sunglasses.