How do I vertically shift letter in the text

Use raisebox with a negative argument to lower text, and I suggest some negative kerning, to fill in the gaps. Finally, stick it in a macro for convenience.

documentclass{article}
newcommandTRENTo{Tkern-.4exraisebox{-.48ex}{R}kern-.40ex ENTo}
begin{document}
TRENTo{} to the rescue!
end{document}

If you want to protect it from changing to different font families or shapes due to the underlying text, then you can put it in a group with the desired font properties, as in

newcommandTRENTo{begingroupnormalfont
  Tkern-.4exraisebox{-.48ex}{R}kern-.40ex ENToendgroup}

Look at the TeX macro definition. TeX has primitive lower or raise followed by dimen and box. The box is shifted by the given dimen (in horizontal mode). You tas can be solved by:

protecteddefTRENTo{Tkern-.4exlower.48exhbox{R}kern-.4ex ENTo}