If you created overrides before you knew about storing overrides in your own Management Pack and need to remove a Management Pack, here's how you can delete a Management Pack that has a dependency on the Default Management Pack. Essentially, you need to export your Default Management Pack, delete both the Default Management Pack and the Management Pack you want to remove, edit (after backing up the file) the Default Management Pack to remove references to the other Management Pack, and then import the clean Default Management Pack.

Detailed instructions are below. In these instructions, the Management Pack you want to remove is referred to as MPToRemove.

Note: This procedure directs you to delete your current overrides and manually edit your Default Management Pack. It's not for the squeamish!

1. Use the console to delete the overrides you've created for MPToRemove. If you don't remember what overrides you've set, try this:
1. Go the Authoring pane on the console.
2. Use Ctrl-M to bring up the scoping dialog and check MPToRemove as your target. Click OK.
3. In the navigation tree, click Monitors.
4. Right click on each Monitor listed and select Overrides Summary.
   
   
5. Click each override and then click Delete.
   
   
6. Repeat steps a-e for the other Management Pack objects. For some objects, the right click menu path is Overrides -> Overrides Summary.
2. Export the Default Management Pack:
1. In the console, go to Administration pane and click Management Packs in the left tree.
2. Right click on Default Management Pack and select Export Management Pack...
3. Make a backup copy of the exported file.
4. In the console, right click on Default Management Pack and choose Delete.
5. Right click on MPToRemove and choose Delete.
6. Edit the Default Management Pack to remove Reference tags that point to MPToRemove:
1. Open the Microsoft.SystemCenter.OperationsManager.DefaultUser.xml file with your editor of choice. I use XML Notepad.
2. Find the References tags at the beginning of the XML . If you're using XML Notepad, you'll find it on the left side under Management Pack->Manifest->References.
   
3. Remove all Reference tags that point to MPToRemove. In this example, I'm unlinking the Active Directory Management Pack, and you can see the text on the right refers to AD.
4. Save and close the file.
7. Import the Default Management Pack back into Operations Manager:
1. In the console, go to the Administration pane.
2. Right click Management Packs and choose Import Management Packs...
3. Follow the instructions to import the Management Pack. The file name is Microsoft.SystemCenter.OperationsManager.DefaultUser.xml.
8. If the import fails, rename your backup copy of the Default Management Pack to its original name, import it, import MPToRemove, and verify that you've manually deleted all the overrides. Then try this procedure again.