Hall Echo has a philosophy problem. Echo is technically the performers own voice arriving at the microphone slightly late having bounced off the walls and ceiling of the hall. So the job of Echo Removal® is to remove the performer from himself.
[Booming kettle drum sound.]
You can mess with Noise Removal and you might get some relief.
https://forum.audacityteam.org/t/mitigate-overdose-of-reverb/35125/1
Koz