If the sunflowers are part of the mix I would leave them in, they make up part of the food balance.
I wasn't familiar with that mix, but from what I can see in the pic and ingredients, it looked like a good variety.
I had a quick look at the hamingway foodmix database (Disclaimer - I only use this as a source of information and you may want to do more research on your own but they do explain how they worked out their calculations, taking each type of hamster food on it;s own merit.)
Choosing an Appropriate Foodmix | The Hamingway
They class the food you are using as a high (good) mix. Although it is for syrians. So you may want to look into getting a food aimed more at a russian hamster. Different species of hamster have different needs.