There is a Noise Gate here Missing features - Audacity Support.
Installation instructions: Missing features - Audacity Support .
It is extremely hard to remove echo. The Noise Gate will only reduce or silence echo between the words of the sermon.
Occasionally you can use Noise Removal to select some echo as Noise Profile then ameliorate the echo that way. That may sound worse than doing nothing.
Please be careful with XP. It is a security risk given Microsoft no longer supports XP with patches. See audacity not saving - #3 by Gale_Andrews
Gale