Any chance that in the future we would be able to delete a field we create in Marketo rather than just hiding it? This would not pertain to SFDC fields.
Per the community article, "You may want to get rid of a field you created in the past if you no longer have a use for it. Unfortunately you cannot delete fields in Marketo, however you can hide them from the user interface."
This needs to get back to the top of the pile as it can become a huge problem. This is especially difficult to deal with when inheriting systems with hundreds of unnecessary custom fields.