As far as I know, you should still be able to change it.
Sign in here https://account.smartthings.com and come back and read this post, Kate.
https://community.smartthings.com/t/changing-device-handler-after-install/49539/2?u=blkwll
If I’m wrong about you having access to the IDE, I apologize, but that would be the first I’ve heard of that.