remove undesirable trim curves from surface

Hey pals,

does anyone know how to remove undesirable trim curves from surface.

I have performed trim operations on surfaces, but some of them are partly trimmed (as on the picture below).

If I use the component 'untrim' but in this case surface goes back to the first stage of  before it was trimmed.

Is there any chance to close up this "scratch" or to delete from history that surface is a 'trimmed surface' or to convert these surfaces to other data types?

best,

Lukasz