What can I do to remove air in water line which has occured after city reapired a broken line?

To remove air from Water lines you simply need to run the water for an extended period of time.

Traditional tank type water heaters will hold air and the air must be gotten out especially if it is an electric unit.

Go to any faucet (preferably one where you have a separate knob or lever for the hot and the cold) and turn it on full blast until you have a solid and consistent flow of water from both the hot and cold water lines. If the Water Heater has emptied you will need to run the Hot Water for a very extended period of time.

The faucet(s) will do a lot of spitting and sputtering and making noise but this is normal and necessary.

Hope this helps!