I deleted the last page from a PDF. I edited the name of the file and saved it. But I have no idea where PDF24 put it, nor how I can specify a save location. This user interface is absolutely horrible. An app should ALWAYS give the user the ability to specify a location before saving a file.
Did you use the PDF24 Toolbox in the PDF24 Creator? The toolbox should ask you where to save the result. If you have used the online tools, then there is the download button. When you click the download button the result is downloaded to you downloads folder. If you have used the PDF24 Creator and you do not get a save file prompt, then please send a test file and screenshots to forum@pdf24.org so that we can check that.