Error 'This extension depends on the package you are trying to uninstall'

If there is a link to the (Package Name) in above error, click on that link to open it.

To delete the package:
 

In Salesforce Classic:

1.  Go to Setup | Create | Packages
2.  Click on the package referenced in the error
3.  Click on Delete
 

In Lightning Experience:

1. Click on Setup | Apps | Package Manager
2. Click on the package referenced in the error
3. Click on Delete
 

Note:

1. There are instances wherein this error occurs in sandbox and if the package pertained in the error is created in Production, the package needs to be deleted in Production first, then refresh the sandbox to remove the dependency, and then uninstall the package.
2. If there is no link to the package, or the package cannot be found in the org under Setup - Create - Packages; or Setup - Installed Packages, please log a case and provide details.


See also: 

• Uninstalling a Package
• Best practices when you uninstall an app or package
• YouTube video: How to Uninstall a Package When There Is an Associated Extension Package