You said : 1 glu ---> 2 lactates, delta Go = -45. What would be the delta Go for 2 pyruvates from glucose?
The 45 figure was for the transformation without considering ATP coupling. I cited the figure of -18 kcal/mole of glucose in the lecture and handout, for the reactions from glucose to 2 pyruvates, including and taking into account the net production of 2 ATPs. If you want to consider the standard free energy change of glucose to 2 pyruvates without making ATP, it would be -18 -(7X2)= -32.

Why didn't you include the calculation of the energy ATP used in the delta Go=-45? If you did, the anwer would be the NET energy and it is = -31?
Yes. I used the figure of 45 without the ATPs in order to calculate the efficiency of the reaction in harnessing energy in the form of ATPs. So you had 45 to work with, you got 14 out of it, 31 were "left over," assuring that the reaction will still go far to the right even after the coupling to the production of 2 ATPs.