How to reduce grain from pictures

[Walikirito]

How does one remove grain from pictures that have less light in them. Can it be accomplished in lightroom or Photoshop. And for future reference how does one prevent this from happening in case of using the pro mode on phone.

 

[Susan06]

Preferably try to use as less ISO in your shots as much as you can that would allow for a lot more difference in grain. But then you'll have to have your subject in a lot of light. That would allow for a detailed and crisp shot.