How can I remove a transparent background from a TIF created in Photoshop with external tools

Most likely the problem in other applications is they don't support layers in tiff files, thus your seeing flattened version of the tiff.

Most non adobe applications don't support layers in the tiff file format and just so you know adobe owns the tiff file format.

If you were to save the same file as a psd, then Gimp, for example, would show the transparency.

Also. while gimp recognizes photoshop's layer groups it doesn't recognize shape layers so they would have to rasterized in photoshop and then saved as a psd.

However, you should simplify your layer structure as much as possible, so other applications can open the file as you see in photoshop. For example, with your image, just one layer containing both rasterized shapes and no groups/artboards would be best. Also, pngs would probably give max compatibility with other applications.

In Gimp you can get back the transparency in the Test.tif by using Colors>Color to Alpha to remove the white background.

https://docs.gimp.org/en/plug-in-colortoalpha.html

In Gimp 2.10 one needs to add an Alpha Channel first before using Color to Alpha.

Right click on the Layer thumbnail and click Add Alpha Channel.

Just to add that if in photoshop one adds an Alpha channel from the selection of the transparency and saves the image as a TIFF that many applications will then open the TIFF with transparency.

gimp 2.8 and older

gimp 2.10

Your test.tif saved as a psd with the shape layers rasterized and open in Gimp.