am i suppose to attack somewhere and purposely loss troops ?
This could be a solution if you really want free pop space (attack an enemy, you'll get Battle Points as well as free pop
).
I don't know how you built your city exactly, but you may also research Plow in the academy, which will give you 200 more population. You can destroy useless buildings (senate does not need to be at max level, same goes for the temple and the market place in my opinion), this will release population. Once you have 60 free pop, build the Thermal Baths, they will give you a supplement of 10% more population
EDIT - I just your other posts. Next time you need to ask a question, just do it once. Posting in every thread related to your problem will not make the answers come faster ;-)