How do I set and delete the center number for my GPS Vehicle Tracker GT06N to cut off/restore oil by SMS command?

How do I set and delete the center number for my GPS Vehicle Tracker GT06N to cut off/restore oil by SMS command?

In case the vehicle is stolen, the users can send SMS command to cut off the Petrol/Electricity to stop the vehicle from moving. 
Note: To ensure the safety of the driver and the vehicle, this command can only be used when GPS is located and driving speed is less than 20km/h or the vehicle is not moving. 
The users can also send SMS command to restore the Petrol/Electricity so that the vehicle can keep moving.

To set the center number:

To cut off or restore oil via SMS command, you must first set a center number. Only the designated center number has the authority to send the cut off or restore oil command to the device. You have the option to set your own mobile number as the center number.  

The command for setting center number is: 
CENTER,A,mobile number# 
For example:CENTER,A,15942703401# 
If set successfully, there is an “OK” reply message. 

Note: Only the SOS number can be used to set center number successfully.

To delete the center number:

SMS command to the device to delete the center number. 

The command is:CENTER,D# 
For example:CENTER,D# 
If set successfully, there is an “OK” reply SMS. 

Note: Only the SOS number can be used to delete the center number successfully. Only SOS phone number can send this command successfully to set the center number. Only one center number can be set.