The description below uses the OTRS version 3.1.1.
Here are the steps to delete a config Item in OTRS.
1. Go to “Admin” tab.
2. Under “Ticket Settings” section, select “General Catalog”. It open up a new screen.
3. Under “General Catalog Management” , from drop down select “ITSM::ConfigItem::Class” and You will Config Items on right”.
4. Click on the Config Item you want to delete. The Config Item would be displayed.
5. Change Valid Option to “Invalid” and save it.
6. The Config Item would no longer be seen in “CMDB” -> Overview.
You can verify the “Config Item” as it would be displayed under “CMDB” tab . Go to the tab “CMDB” and click on “OverView”. You will see the “Config Item” that you deleted is no longer available.