3GPP 24.501 v20.0.0 — the document's own text
6.4.3.3 UE-requested PDU session release procedure accepted by the network
Taught in 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
Upon receipt of a PDU SESSION RELEASE REQUEST message and a PDU session ID, if the SMF accepts the request to release the PDU session, and shall perform the network-requested PDU session release procedure as specified in clause 6.3.3.