You can use the SQLLocalDB utility to list the SQL LocalDB instances on your computer.

In my case, for SQL Server 2019, I located the utility at C:\Program Files\Microsoft SQL Server\150\Tools\Binn\SQLLocalDB.exe. If you have this tool installed, executing the following command in the command prompt will provide you with a list of LocalDB instances:

sqllocaldb.exe i

To uninstall a LocalDB instance, use the following command in the command prompt:

sqllocaldb.exe d nameofinstancetoremove

This allows you to manage and remove specific LocalDB instances as needed.