draw a line under something
 US /drɔː ə laɪn ˈʌndər ˈsʌmθɪŋ/
 UK /drɔː ə laɪn ˈʌndər ˈsʌmθɪŋ/

1. 
終止符を打つ, 区切りをつける
to consider something to be finished and to not think about it or discuss it anymore
:
• 
It's time to draw a line under the argument and move on.
議論に終止符を打ち、次に進む時が来た。
• 
Let's just draw a line under what happened and start fresh.
何が起こったかに終止符を打ち、新たに始めよう。