After 30 days you can't click on go back to sketchup 2016

After upgrading from sketchup 2015 to Sketchup 2016, it automatically installed Sketchup Pro 2016 for 30 day’s but aftyer the 30 days wanted to go back to sketchup 2016 but the “I Agree” is down the bottom off the page and you can’t shrink it or move it up emough to click on exit or I agree. get it sorted