[descaul]

I've been trying to edit a piece of music imported in PDF form. I can't get the erase to work in any of the three forms, but it may be that I have got
the wrong end of the stick. Does the erase only apply to whatever annotations have been added, or can you erase some of the items in the original PDF file.
I've managed to do this using the snipping tool: both snipping out a piece and even moving the piece about on the page. But I can't get erase to work on both the
Android and Windows 10 versions.

[McAroni]

The erase Tool is designed only for annotations you made in the file. You could cut out parts with the snipping tool. But this does not Really cut  things out. It makes a white overlay to cover the part you "cut" out.