I read it in an anthology book in 1975. When not attacking planets the pilot has more freedom to think and does not like what he does during the raids, but before the raids start he is injected with chemicals and drugs that make him forget his own thoughts and reinforce his feelings of aggression and victory and superiority. This may have been in a book edited by Roger Elwood, but I am not positive.
"City of Yesterday" by Terry Carr; first published in If, December 1967, available at the Internet Archive. You probably read it in the Silverberg-edited anthology Beyond Control whose contents also included Philip K. Dick's "Autofac". From the story:
As the destruction continued, he felt more and more the oneness, the wholeness of machine and man. Charles the other-thing was gone, merged into his own being, and now he was the machine, the beautiful complex mass of metals and sensors, relays and engines and weaponry. He was a destruction-machine, a death-flier, a superefficient killer. It was like coming out of the darkness of some prison, being freed to burst out with all his pent-up hatreds and frustrations and destroy, destroy . . .
It was the closest thing he had to being human again, to being . . . what was the name he had back on that planet where he'd been born? He couldn't remember now; there was no room for even an echo of that name in his mind.
He was Charles.
He was a war-machine destroying a city—that and only that. Flight and power occupied his whole being, and the screaming release of hatred and fear within him was so intense that it was love. The attack pattern became, somehow, a ritual of courtship, the pyrobombs and destruction and fire below a kind of lovemaking whose insensitivity gripped him more and more fiercely as the attack continued. It was a red hell, but it was the only kind of real life he had known since the machines had taken him.
When the battle was over, when the city was a flaming circle of red and even the beams had stopped firing from below, he was exhausted both physically and emotionally. He was able to note dimly, with some back part of his brain or perhaps through one of Charles' machine synapse-patterns, that they had lost three of the fliers. But that didn't interest him; nothing did.
When something clicked in him and Charles' voice said, "Remove your muscle contacts now," he did so dully, uncaring. And he became J-1001011 again.