clipping path

Image Trace?

defaultc,

On second thought, I would suggest your leaving the signature unchanged, and if you must, you can add a page with a black background behind the C Wagner and a note.

Apart from any legality/authenticity considerations, I find it much better and livelier with the actual signatures as they are.

What you need are the clipping paths and what's inside the mask needs to go, right?

I would first copy that signature to a new file. Then select all and release the clipping paths. The masks are now (most probably) easy to find: they are all no fill, no stroke. Select one of them and Select > Same > Fill & Stroke.

I would then first cut them from the new file, delete everything else and then paste in again.

Then in the Pathfinder panel click on Unite.

defaultc,

It looks like a very easy job in Photoshop, starting with Brightness/Contrast, then recolouring.

But it also looks like a possible legal/authenticity issue, including this: what would (the descendant(s)/successor(s) if any, of) C Wagner/any other relevant parties say to it (that of CE (/) Eriksen presumably unchanged)?

The quick way to release clipping masks would be to select all the paths and release them (object>clipping masks>release or CTRL/CMD+SHIFT+7). But I doubt it will acheive what you want to do (it will show the whole shapes, not clipped.
One good way would be to select the shapes and try the path finder

with the "intersect" option, and see what it does. Depending on how your shapes are built, it can work, or you'd have to do it section by section. All the end you can "merge" everything .

You could also select everything again and use the "shape builder tool"

drag the mouse across the shapes you want to keep, and drag across with alt held down to eliminate all unwanted shapes.
https://helpx.adobe.com/uk/illustrator/using/creating-shapes-shape-builder-tool.html

Hope it helps!