Screenshot of the featured snippet for a Google search of "godot delete pattern". It reads: "You can right-click any tile to remove it. If the eraser is selected (press 'E' while the TileMap is selected) left-clicking a tile will also delete it. To remove multiple tiles at once you can use the Line, Rect or Fill tools (press 'L', 'R' or 'F' while the TileMap is selected)" Even more so, the part "right-click any tile to remove it" is highlighted by Google. While none of this is wrong, it is *not* the answer to the question of how to delete a TileMap pattern.
https://cdn.masto.host/mastodongamedevplace/media_attachments/files/112/490/456/501/847/262/original/f84deed8418a9398.png