Sure...
This time I removed and then restarted DW. Last time I removed and reinstalled without restarting in between.
Restarting after removing the Extension via DMX now sows the "Uniinstalling DataBridge" dialog.
ANOTHER restart of DW now shows removing MySQLi as a new separate event...
Next I add the extension but it does not show in the list on DMX Ext manager. MySQLi behaviour is there though so maybe I should delete that separately? (Screens attached)