Unable to delete or rename folders in contacts
If you are referring to Local Folders > Contacts, this is a system folder and cannot be deleted.
If that is not what you meant, can you maybe post a screen shot indicating which folders you want to delete, and who your contacts provider is.
Unfortunately you cannot delete or rename a Google System folder.
The only way to remove this error from re-appearing is to remove the Gmail account from eM Client, then add it again. Then try and avoid changing it again.