You can delete the configuration so long as it is not the active configuration or is not being used in another assembly or drawing. If it does not let you it usually means one of the two things above is occurring. If that is the case then just close all the other files that might be using that configuration and try to delete again. Be aware if the configuration is being used in an assembly the part will automatically re-link to another configuration. Same with a drawing. This might mean you will have to do some work to get things looking how you want them again.
You can delete the configuration so long as it is not the active configuration or is not being used in another assembly or drawing. If it does not let you it usually means one of the two things above is occurring. If that is the case then just close all the other files that might be using that configuration and try to delete again. Be aware if the configuration is being used in an assembly the part will automatically re-link to another configuration. Same with a drawing. This might mean you will have to do some work to get things looking how you want them again.
Ryan W.