We don't store the owner key nor the master password on Keychain so we cannot do this directly via Keychain.
If you feel comfortable with code, you could follow this :

@r351574nc3/tutorial-changing-your-recovery-account

Basically this line:

  hive.broadcast.changeRecoveryAccountAsync(ownerKey, user, new_recovery_account, [])

hive being the hive.js library in this example