Stupid question about child theme

Hi all,
this is a newbie question about theme child stuff.
I just need some confirmation to stay safe about a live site.

I installed both agama and agama blue BUT I’m using the last one.
May I unistall agama theme safely or I need it phisically present on the fs as well?
Now, about their update: based on previous question, do I follow some specific / prioritized steps for updating parent and child theme?

Be patient, I never used a child theme before.

Thanks,
A.