While ST Pro is a brilliant piece of software it is not a magic wand for audio.
There are audio that can not be fixed. People try very hard to get room and hall reverb into their projects but an echo is annoying and distracting, depending on the report back timing.
In a recording that runs linearly, there is noting you can do except try to replace the echo report with dead air but generally this is impossible when you have constantly updating audio coming from the source.
If some one speaks - HELLO and the reply is hello..hello then there are two reflective surfaces to deal with.
If some one speaks Hello my name IS - and you get ..Hello my name IS...Hello my name IS, there is no good way to mask the back report for each word.
Does that make sense?