How to cancel the set SMS ringtone for OPPO mobile phone?

Take OPPO R9S mobile phone as an example. The logout method is as follows:

First, click the "Settings" icon on the desktop of OPPO R9S mobile phone to enter.

Second, select the "sound and vibration" option after entering.

Third, then select the SIM card to cancel the SMS ringtone. Take China Telecom 1 as an example, and click Enter.

Fourth, after entering, check the "None" item.