Login to you plesk panel.
Click on the Websites and Domain left side of the page.
Click on the domain for you which you want to add the account, and click on FTP access.
On the FTP page, click on ADD FTP account.
To delete FTP account you can choose the.
click on Remove.
At the Remove the selected FTP accounts? prompt, click Yes.The account (or accounts) you choose are deleted by Plesk.