How to add previous session host back to WVD

I have setup WVD with host pool and new WVD is running and I am able to access both the whole RDP and remote app.
but I did mistake to remove session hosts under host pool configuration.
How to add previous WVD(vm) back to session host under host pool.

Thanks

Fang zhiyong

Original post https://docs.microsoft.com/en-us/answers/questions/43315/index.html.