Chapter removal mkv

[zkab]

I have one mkv file with 15 chapters.
When I run 'mkvextract' all the chapters are shown like:

<?xml version="1.0"?>
<!-- <!DOCTYPE Chapters SYSTEM "matroskachapters.dtd"> -->
<Chapters>
<EditionEntry>
<EditionUID>801521038</EditionUID>
<EditionFlagDefault>0</EditionFlagDefault>
<EditionFlagHidden>0</EditionFlagHidden>
<ChapterAtom>
<ChapterUID>280084908</ChapterUID>
<ChapterTimeStart>00:00:00.000000000</ChapterTimeStart>
<ChapterFlagHidden>0</ChapterFlagHidden>
<ChapterFlagEnabled>1</ChapterFlagEnabled>
<ChapterDisplay>
<ChapterString>Overture</ChapterString>
<ChapterLanguage>und</ChapterLanguage>
</ChapterDisplay>
</ChapterAtom>
...

but when I try to remove some chapters with 'mkvmerge GUI' all in tab 'Chapter Editor' are grayed out and no chapters are shown.
I have Linux Mint 3.2.0-4-amd64 and MKVToolNix 6.1.0
How can remove some chapters ?

[sneaker_ger]

How exactly are you trying to open the file in the chapter editor?
Often people are confused because the chapters of the mkv files they added to the source tab are not shown in the chapter editor. That's because the chapter editor is more or less a program of its own. Click "Chapter Editor" in the menu at the top and select "Load" or drag & drop the mkv file into the chapter editor (not into the source tab). After removing some chapters you have to click "Chapter Editor" again and select "Save to Matroska file".

[zkab]

:thanks:
It worked just great ...