How to completely restore the factory settings of Nubian mobile phones?

Take Nubian Z 17 mobile phone as an example, and the specific methods are as follows:

First, click "Settings" on the desktop of Nubian Z 17 mobile phone, as shown in the figure below.

2. After entering the settings, select the "Advanced Settings" option, as shown in the figure below.

3. After entering the advanced settings, click "Restore Factory Settings" to enter.

4. After entering, turn on the switches of "Format cell phone storage" and "Delete application", and then click "Restore cell phone factory settings".