selecting part to delete

OK see now re

The cut-intervals automatically collapsed when you work in a "Cut" mode.

and

You can collapse the cut interval manually in your mode - just double-click the cut interval and you'll see how collapsing works.

Hello isurfsafe,
From your screenshot I can see that you have "Keep" mode selected. which means that the begin marker would set a beginnig of the "Keep" interval, and end marker sets the end of the "Keep" interval. The cut-intervals automatically collapsed when you work in a "Cut" mode.
You can collapse the cut interval manually in your mode - just double-click the cut interval and you'll see how collapsing works. To expand the interval back you should double-click the collapsed marker.
The interval which is bright is considered a "keep" interval, the one that is dark is the "cut" interval.

don't know why they call this support forum . no support

How do you know which is the selected part with video splitter 6.1.1705.18?  what does collapse mean?. is collapsed part  the darker part - the part to delete?.
Also when i select the End  marker the marker goes all the way to then end of the video not to where the cursor is?
The pdf says
After placing the End Marker the selected fragment will be collapsed. So you will see the special one line instead of two lines of Begin/End Marker depicts the collapsed fragment.
What is the special one line instead of two lines?

Good program. Far too complicated. I suggest you put a green filter  over the parts that will be saved and a red filter over the parts that will be deleted like this https://ibb.co/hKRf59