You can "grow out of symptoms" by recognizing them and taking action of it. Its the way that the brain thinks, acts, and responds. I thought I grew out of it, but I just learned to recognize and adapted according. Its different for everyone so learn about what makes you unique and adapt accordingly

ADHD is something you never really "grow out of," because even adults are diagnosed after years of medical silence. I don't take meds for my ADHD, but people consider you "grown out of" it when you don't rely on meds and can manage the symptoms on your own. Like Rodent said, it's all about learning to recognize your mental processes and practicing taking agency against the negative habits your ADHD contributes to.

You don't grow out. It is a very real condition. It is a thorn in my side.

It's a neurodevelopmental condition, it doesn't really go away, you just can sometimes adapt to how you have already been coping. I'm 30 and wasn't diagnosed until 22 even though I have had symptoms forever. Meds are incredibly helpful and there isn't anything wrong with continuing them into adulthood.