sudo apt-get install postgresql

Step 6: Create a Database User Role for Handling Odoo Databases

Next, a password for the distinctive user should be defined, which is needed later in the conf file:

sudo su - postgres

createuser --createdb --username postgres --no-createrole --no-superuser --pwprompt odoo15

Make the defined user a superuser

psql

ALTER USER odoo15 WITH SUPERUSER;

And Exit from psql and also from Postgres user

\q

exit