So I have a door like this but I don't want the drawer part anymore. Is there a way I could join them to be one piece without it looking too ugly?
How about a couple of these: https://www.ebay.co.uk/itm/Kitchen-Door-to-door-and-Drawer-Jointing-connecting-joining-plate/360987000299
They wouldn't work because you need to maintain a distance between drawer front and cupboard door for appearance's sake. Some joint plates even have small projections to maintain the gap between the two.
Wouldn't use dowels, much more difficult to fit and less secure I would have thought; and as Willy said you need the gap to maintain the appearance.
Great advise. Glad I consulted the experts. The width of the door is 60cm. Would 2 joint plates be enough?