11.3 First Marker - From DOD Law Of War Manual (Page 811):
11.3 END OF OCCUPATION AND DURATION OF GC OBLIGATIONS
The status of belligerent occupation ends when the conditions for its application are no longer met. Certain GC obligations with respect to occupied territory continue for the duration of the occupation after the general close of military operations.

https://dod.defense.gov/Portals/1/Documents/pubs/DoD%20Law%20of%20War%20Manual%20-%20June%202015%20Updated%20Dec%202016.pdf?ver=2016-12-13-172036-190

11.3.1 End of Occupation. Belligerent occupation ceases when the conditions for its application are no longer met. In particular, as discussed below, the status of belligerent occupation ceases when the invader no longer factually governs the occupied territory or when a hostile relationship no longer exists between the State of the occupied territory and the Occupying Power.

Belligerent occupation ends when the Occupying Power no longer has effectively placed the occupied territory under its control. For example, an uprising by the local population may prevent the Occupying Power from actually enforcing its authority over occupied territory.Similarly, the Occupying Power’s expulsion or complete withdrawal from the territory would also suffice because the former Occupying Power generally would not be able to control sufficiently the occupied territory.