Even if you delete unnecessary world data from the save data list in the game, it will be deleted by appearance, but it seems that it is not actually deleted from the save data of the XBOX main unit.
The data remains in the XBOX console, and when you start the game again, it is grayed out and the data still exists.
Since the data will continue to remain, it is squeezing the data area of the XBOX main unit.
Even if you try to delete unnecessary data from the storage list in the settings, the data will continue to remain.
If you delete unnecessary worlds from the game storage settings, the save capacity will decrease in the game, but if you check the save data from the add-on management of the XBOX console, the capacity before deletion has not changed.
Please resolve it as soon as possible.
Please do not duplicate your reports (MCPE-158659). If you have new information to add, you can edit the original report.