To make changes in DNS Zone, please follow the following steps :-
1) Login to your Plesk control panel.
2) Click on "Subscriptions".
3) Click on "Manage Hosting".
4) Click on "Websites and Domains".
5) Click on the DNS Settings.
6) Click on [Manage] in the front of that domain name only.
7) Click on any dns record which you want to delete or modify. i.e. marked in RED
8) Once you have made the changes.
Clik OK and you get in Green Bar {Changes made to DNS records were saved.}
9) Click on "UPDATE" to apply the changes.
Information: Changes made to DNS records were saved.
