Why can't I inactivate a position in Workforce Modeling?

Because the position you want to inactivate either has an active or suspended incumbent as of the effective date or in the future.

To inactivate a position with incumbents, you can either move incumbents out of the position or terminate the incumbents and then inactivate the position. If you implement a model with inactivated positions, then this position will not appear in the HCM position hierarchy.