Arabic to English Social Sciences Law (general) Judicial work

I'm struggling to understand the phrase تنازل ممن لا يملك على ما هو غير مختص به in a document about Egypt's cession of Tiran and Sanafir islands to Saudi Arabia: https://www.yumpu.com/xx/document/view/56768915/-/13 (middle of page 16).

The complete sentence is:

فقد أكدت المحكمة مصرية الأرض، ومن ثم أبطلت الاتفاقية لكونها تتضمن تنازلا ممن لا يملك على ما هو غير مختص به إلى من لا يستحق بالمخالفة لصلاحيته ولنصوص الدستور

I think the idea here is probably that the agreement include a cession "by someone who doesn't own [the land] of something that it has no competence/jurisdiction over". However, the phrase is unclear to me, especially the use of على when I expected عن (the preposition that usually goes with تنازل).

Any ideas? Thanks.