Suppose I have a character vector like
\"Hi,  this is a   good  time to   start working   together.\". 
I just want to have
gsub is your friend:
test <- "Hi,  this is a   good  time to   start working   together."
gsub("\\s+"," ",test)
#[1] "Hi, this is a good time to start working together."
\\s+ will match any space character (space, tab etc), or repeats of space characters, and will replace it with a single space " ".
Another option is the squish function from the stringr library
library(stringr)
string <- "Hi,  this is a   good  time to   start working   together."
str_squish(string)
#[1] ""Hi, this is a good time to start working together.""