x <- "Google in theee lland of whhhat c#, c++ and e###"
gsub("\\S*(\\S)\\1\\1\\S*\\s?", "", x)
# [1] "Google in lland of c#, c++ and "
(\\S)\\1\\1
finds sequences of three consecutive repetitions of a single non-space character.
The surrounding \\S*
and \\S*\\s?
just capture preceding and succeeding characters within the same word, as well as any single space immediately following the word.