Whats the correct way to remove all links (including appdata) to a serialport

I often create a serial port object, s and save it from a button callback using

s = serialport('COM2',19200)
setappdata(0,'serial',s).

I understand using the new serialport there is no need for fclose(s).

Whats the correct way to clear up both the serialport object and the appdata (from a seperate button callback that created the serialport object)

Is it

    1. S1=getappdata(0,'serial')
    2. delete(S1) 
    3. clear S1
    4. rmappdata(0,'serial')

Thanks