Morph targets tied to skeletons (unless I am mistaken) cannot have their morph target removed (doesn’t work in UEFN, delete does nothing) and morph targets will create a UEFN validation error, meaning if you have a marketplace asset with a morph target, you simply can’t use it.
Editing in UE5 doesn’t work either, because the morph target is stored on the model.
EDIT: I found a way to work around this issue if anyone is interested, you have to open the skeletal mesh and skeleton in UE5, delete the morph target from there, and then export it as an FBX file, then import it into UEFN.