User Configuration > Administrative Templates > Microsoft Project 2016 > Project Options > General
User
HKCU\software\policies\microsoft\office\16.0\ms project\options\general
Limits the number of actions (1-99) that a user can undo. If you enable this setting, you can set a limit on the number of actions (1-99) a user is can undo. If you disable this setting or do not configure it, the user's default setting is used.