I want to clean out my laptop

[Romulator]

As the title says, I want to clean it out of everything and restore it all back to how I got it, but keep anything it needs to run software wise.

But this being the first time attempting this, what stuff do I need and what process should I follow, as there is like half a million different tutorials on it. I am running Windows 7, 64-bit.

If I need to provide anything else, let me know