cannot delete files and folders with long names in windows

I have used FBackup to backup to my external hard drive and now I am trying to delete this backup from the external hard drive but it wont allow me.

There is at least 100Gb of data and I can delete the culprit files if I dig deep and then go an rename that folder to a shorter name but I don't want to have to do this for 100Gb of data.

Is there a utility I can use to sort this out with please?

Thanks