Go to Control Panel -> Add/Remove Programs.
Select Netspan V8 and click the 'Remove' button.
If the existing Netspan version was a 'Standard Network Server' installation, a popup window will ask you if you want to keep the existing Netspan database. In order to upgrade a 'Standard Network Server' installation, you must keep the existing database, and answer 'Yes' to this question. Whichever option you chose, the existing Netspan database will automatically be backed up in: 'C:\Program Files\Airspan\Backup Files'.
The installer automatically removes the installation from your machine.