Hello Osama,

Please refer below link, i think below blog can help you with steps but you can do it in your local machine and not on cloud environment 

My Journey with DB Connector in Mendix / PostgreSQL | by Pratiksha Bhaskar Gaikwad | Mendix Community | Medium

Thanks

Hi,

Kindly check the Restore a Backup Locally Mendix Doc to connect postgres with Mendix

https://docs.mendix.com/developerportal/operate/restore-backup-locally/ 

Hope it helps!!!

You do not have access to your application's database on mendix, update, delete records directly, what you can do is download a backup of your database, restore it to your local machine, make the desired changes, create a new one backup, and restore this new backup to your mendix cloud environment.