Tasks can be made inactive

This policy setting will allow tasks to be inactivated.

If you enable or do not configure this policy setting, users will be able to use the Inactive tasks feature, and tasks are allowed to be inactivated.

If you disable this policy setting, tasks cannot be inactivated.

Supported on: At least Windows 7
Registry HiveHKEY_CURRENT_USER
Registry Pathsoftware\policies\microsoft\office\15.0\ms project\options\scheduling
Value Namecanmakeinactivetasks
Value TypeREG_DWORD
Enabled Value1
Disabled Value0

proj15.admx

Administrative Templates (Computers)

Administrative Templates (Users)