Here are four ways to delete images:
(1) Click with the left mouse button on the image, so that it is selected. Then click Main menu ⁄ Edit ⁄ Delete or press the keyboard Del key.
(2) Position the text cursor just past the image, e.g. by clicking there with the mouse, then press Backspace. The image is deleted in the same way as a text character.
(3) Right-click the image, then click on 'delete' in the article popup menu.
(4) By converting an article to plain text you also remove all images from it, since TreePad considers them to be included in the formatting. Of course, you cannot use this if you wish to preserve text formatting. You have the choice of converting just the current article, or all articles in the current node's subtree (including the current article) to plain text in this way.
Methods 1, 2 and 3 can be reversed by clicking Main menu ⁄ Edit ⁄ Undo or pressing Ctrl+Z, as long as you do not open another article.