After renouncing the use of and later experiencing the further removal of any titles, honors and military ranks, Andrew Mountbatten-Windsor’s armorial bearings revert to those granted to him originally before any other honors or titles were bestowed upon him.

That is, the royal arms differenced by a label of three points (for the son of a Sovereign) the center point of the label charged with a blue anchor. The Royal arms, suitably differenced, are allowed to be used by him as the son of the Sovereign at the time of his birth regardless of any removal of his titles and honors.

I had wondered if he would be allowed to continue to use the supporters and the crest but apparently he is.