Use the following steps:
mysql -uadmin -p`cat /etc/psa/.psa.shadow` psa -e"update misc set val='false' where param='admin_isPrefEdit';"
mysql -uadmin -p`cat /etc/psa/.psa.shadow` psa -e"update misc set val='false' where param='psa_configured';"
Then log in to Plesk. You will be requested to enter the host name.