To change the default Postgres password in ServiceDesk Plus,
Shut down ManageEngine ServiceDesk Plus. Open the command prompt with admin privileges and execute the command shutdown.bat. Alternatively, you can stop the application by navigating to services.msc.
Take a backup of the application [OR] snapshot of the server.
Execute the steps given below:
Open command prompt with admin privileges. Go to [SDP-Home]bin directory and execute the command
Then execute the command
The following message is displayed:

Finally, execute the following command to start the application services:
Go to [SDP-Home]/bin and execute the command
Then execute the following command
Finally, execute the following command to start the application services.
You have now successfully changed the default Postgres password. Start the application to access the helpdesk.