Your description is a little confusing.. LOL
however I know exactly what your talking about. i researched as well and from what I found it IS designed as a "meant to be removed" piece.. like a factory screen protector.. i left mine on until it slowly got air pockets underneath it than couldn't handle it and peeled it off... slide action is a little smoother after i removed it as well
Was on the phone with support yesterday on a separate issue and I asked them about that plastic behind the screen. It had been hanging up my opening and shutting of the keyboard. They said it's designed to be removed.
I kept mine on the phone for as long as possible, I didn't want my slide to get loose as I had heard some people complain about. After a few months I had to remove it and it did not effect the sliding operation in any way.