Sponsors & sponsees
Your sponsor and the people you sponsor are chosen from your own contacts. Each program has one sponsor. Anyone you sponsor lives on the Sponsorship tab, kept separate from Programs, which is about your own recovery.
Picking someone from Contacts
Picking a person needs no special permission - the system contact picker runs outside the app and hands back a single contact. If you separately grant Contacts access, the app can keep that person's name and number current as they change in Contacts. It never writes to Contacts.
Ending a sponsorship
A sponsorship can be ended without deleting the person. It's archived instead, and moves to past sponsors or past sponsees, where you can see it or come back from it later.