SYMPTOM:
Consider that a form called 'TESTING' has been added to the Form Categories of a project through Strategy Developer 9.4.x-10.x:

Consider that a Freeform SQL report uses this form as shown:

If the form is attempted to be removed by going to Schema menu > Form Categories, the following error comes up:

Attribute Form object 'TESTING' (ID:xxxxx) cannot be deleted because other objects depend on it.

CAUSE:
The form is not deleted from the metadata because of the dependent object, but it gets removed from the project schema object. The Form Categories window only shows those forms which are part of the project schema. Thereby, this does not result in a metadata inconsistency, but the Strategy Developer 9.4.x-10.x interface seems to portray one since an attribute form which does not show up in the Form Categories window is being used in a report.
This is a known issue with Strategy Developer 9.4.x-10.x.
ACTION:
Strategy will continue to investigate and post updates as soon as they are available.