You can enable/disable comments on future posts by going into your Discussion settings.
If you have more than one site, go to My Sites and select the site you would like to enable/disable comments for, then go to Settings.
Next, click on the Discussion tab.
Under “Default article settings,” check/uncheck the box next to “Allow people to post comments on new articles,” and then click “Save Settings.”
And you’re done!
Automatically Closing Comments
It’s possible to turn comments off automatically after a specific number of days. To do this, visit the Settings → Discussion page and look for the “Other comment settings” section. Check the box next to the option specified below, fill in the number of days, and click “Save Settings.”
On Pages comments are disabled by default, but you can enable them when publishing a new page or editing an existing one.