[Closed] Help! Changing Fork on Rockhopper circa 13/14

I wanted to change the fork on my Rockhopper . It has a tapered headtube with an adapter in the lower race to accomodate its current RSxc30 with 1 1/8 steerer. The new fork I want to put in has a tapererd steerer so no need for the adapter anymore but apparantly the lower headset race is integral to and part of the frame (headtube). I originally thought I could just get a lower 1.5 replacement headset to facilitate the change of fork but now i don't know what to do. Any help advice gratefully received.