Just have a look at the help files:
If your computer are managed by LDMS with Patch Manager
If you want to remove LANDesk Antivirus from managed devices, you can also do that as a separate task from the Security and Patch Manager tool.
To remove LANDesk Antivirus
- In the console, click Tools | Security | Security and Patch Manager.
- Click the Create a task toolbar button, and then click Remove LANDesk Antivirus.
- Enter a name for the task.
- Specify whether the installation is a scheduled task or a policy-based task, or both.
- If you want to display the installation progress in the security scanner dialog on target devices, check the Show UI option.
- Select a scan and repair settings from the available list to apply its reboot configuration to the task you're creating. You can create a new setting or edit an existing setting by clicking Configure. The task will use the selected scan and repair settings' reboot options ONLY, which determine reboot requirements and actions on target devices during LANDesk Antivirus agent removal.
- Click OK.
Since you have a standalone computer I would assume you don't have access to the core server it was installed from.
If the computer still has the other LANDesk Agents installed, you can do the following:
Go to Start --> Run --> and type "C:\Program Files\LANDesk\LDClient\vulscan /removeav /showui"
This will launch a dialog and say it is attempting to contact the core server. Contacting the core server will time out several times and then you see that it is removing LANDesk Antivirus.