I would recommend removing it tomorrow morning and only replacing it in the evening.
You should try and convert your birds to a healthier diet that doesn't just consist of seed and if they are only consuming millet now, that's not great.
Please read through stickies on the diet and nutrition section to educate yourself on the benefits of an overall healthy diet that will help your bird.
On thing you should see is that birds need a small amount of seed daily. If your birds are always allowed to eat millet they might be filling themselves up on millet and ignoring the seed for just millet spray.
How much millet do you have in their cage?
A comparison for you to consider is that I give eight birds one spray of millet to share between them all, once a week as a treat.