Deleting extraneous layers via script?

Hi there,

I'm looking for a method of deleting unused layers (in this instance, all layers that don't contain "w2g") with script,

is there a way of doing this? Or am I going to have to find a different way to specify the surplus layers?

I'm really a novice at writing any kind of JS, so anything is really appreciated! Just remember to explain it like I'm five!

Thanks