Replying to Cleaning the rear element of a lens

I just bought a used tamron 17-50 off craigslist for 300 bucks.
I knocked the seller down to 300 because it had some dust on the front and rear elements off the lens.
I just removed the plastic part and then the 4 screws on the front element to clean it.
I then removed the back element 4 screws and can not find how to lift up the rear element to clean it.
Anyone know how to clean the rear element? Maybe there's some youtube videos?? I cant seem to find any...

thanks