Sometimes, to uninstall a feature, we need to uninstall it by its GUID rather than by its Feature Name. This can happen if the feature was originally installed using its GUID and not by the Feature Name. The Folder Name corresponding to the feature in such a case will be this GUID.
To delete a feature with its GUID, use this stsadm command:
stsadm -o uninstallfeature -id [Feature_GUID] -force