How do you get all toc-markers away in 1 time

When i go to toc.ncx and i want to get all toc_markers away how do i do that in one click?

From

<content src="Hoofdstuk-04.xhtml#toc_marker_9789021402437_-2"/>
</navPoint>
<navPoint id="navpoint3" playOrder="3">
<navLabel>
<text>Vier dagen eerder</text>
</navLabel>
<content src="Hoofdstuk-05.xhtml#toc_marker_9789021402437_-3"/>
<navPoint id="navpoint4" playOrder="4">
<navLabel>
<text>1</text>
</navLabel>
<content src="Hoofdstuk-06.xhtml#toc_marker_9789021402437_-3-

To

<content src="Hoofdstuk-04.xhtml"/>
</navPoint>
<navPoint id="navpoint3" playOrder="3">
<navLabel>
<text>Vier dagen eerder</text>
</navLabel>
<content src="Hoofdstuk-05.xhtml"/>
<navPoint id="navpoint4" playOrder="4">
<navLabel>