Before starting any Firebird installations, it is advisable to uninstall any previous Firebird versions. To uninstall any Firebird servers, go to Programs and features in Windows Control Panel, Select Firebird Featured Project file, right click and click on 'Uninstall'. To uninstall Firebase on a Linux system, first go to the start menu, open the Terminal and run the command '$ sudo apt-get remove firebird-server'
Before taking down and uninstalling the Firebase database on your system, make sure that you back up all your databases in order for you to restore them later under Firebird 3.
You can also back up your old security database 'security2.fdb'. Inside the firebase SQL script security_database.sql which is located in (misc/upgrade/security) you can update the old security database to Firebird 3, preserving all the information except SYSDBA's and except any passwords.
Make sure that you have a running Windows or Linux operating system which runs, a good network connection and administrator privileges on your system.