Where do you see this grayed out option - on 'Permissions' tab or in 'Edit access rights' dialog? If on Permissions tab, try to right-click on the folder/workflow in the inventory tree view in the left pane and invoke 'Edit access rights' from the context menu.
Also, check what is the value in the 'Owner' column in permissions table - Parent or This Object. Permissions set on some objects are automatically propagated from the parent object down to all child objects, and need to be deleted on the parent.
When you say 'still doesn't allow me to edit or delete the workflows' do you want to delete workflow permissions or the workflow itself? If the latter, is this workflow your custom workflow or a workflow coming out-of-the-box with vRO installation (these workflows are sealed and cannot be deleted/modified by the user)?