If the rooster is the same age as the little chicks, then the answer is no.
Older, larger chickens harass younger, smaller chickens. It is the law of the pecking order.
Being a rooster will not prevent this. Very aggressive roosters show that behavior earlier, but still, a larger hen will peck down a younger bird.
All you can do is keep the birds separated but visible to each other. When they are old enough to safely introduce, usually about 8 weeks, or at least half size, then you can integrate the flocks leaving plenty of spaces for the younger birds to hide.
Also be sure to have separate areas for food and water so the large birds cannot haze away the younger birds from necessary nutrition and hydration.
As to keeping your rooster, that depends on your goals. If he is a nice, well tempered bird that you want to breed from, of good health and quality, then by all means keep him if you'd like to have fertile eggs.
A good rooster can help keep a flock calmer and keep a look out for predators (though they won't necessarily lay their life down for the hens).
A poor rooster is a menace to all.
If you don't need fertile eggs, and this fellow begins to show signs of being very aggressive with the hens, or worse, human aggressive, then re-home or cull him. It isn't worth the head ache.
LofMc