How do I downgrade from Windows 8 to 7 SSD

I'd like to downgrade from windows 8.1 to windows 7, however im on a Kingston HyperX 128gb SSD 

This ssd currently has windows 8.1 on it, however I want to downgrade it to windows 7, without damaging/affecting the ssd

I will be installing via USB as I don't have a DVD Drive


Is there any method that would ensure I do it properly? As I am lost and dont know how to do this, and what to format, or any partition knowledge

Thanks! Any help would be much appreciated!

the instal media will do everything for you, you don't have to do anything special