Child Themes on Multisite Help

Hi,

1.I activated only child themes to be used by the users VIA Pro Sites premium themes feature.

But I just want to remove the text "This is a child theme of (theme name)"

I attached a screenshot too. How do I get rid of that in all the child themes?

2. I use themes from various sources like Elegant themes etc, am I free to use their theme description?

Kindly help.