To Change Subscription's Subscriber in the Plesk, please follow the following settings:-
1) Login to Plesk control panel.
2) Go to "Subscriptions"
3) Click on Check box of "Required Subscription" in the list.
4) Click "Change Subscriber."
5) Select a New Subscriber and then click Next >>.
6) Review the information about the changes to be made to the subscription settings.
7) Click on Finish.
Information: Subscription ownership was changed.
