Enable SSH Terminal for FTP user within Plesk

1) Login to Plesk
2) Click on Domains
3) Click on your domain
4) You will see the SSH Terminal for your domain is disabled
5) Click on Setup
6) Select /bin/bash for Shell access to server with FTP user's credentials
7) Now you can use the SSH Terminal within Plesk by clicking on the icon or preferably use a SSH Application such as Putty (PC) or Terminal (MAC).