Effectively sealing a game

Hey everyone,I just had some games which started me gaining a lead 10:0 kills for our team and 3:0 towers,however the game ended up lost because we could not end it properly,what are some effectively ways to seal a game like that,is all midding at 10-12 minutes viable? Thank youu! [slayer-jinx-wink] P.S. silver-gold elo