Deleting marked region from a clip - what are the 'markers'?

[21tones]

I want to delete one bar of audio from a clip. Bar 69 as it happens.
Having read the user guide and reference guide I don't understand how to 'mark the region' i.e. my one bar. When I know how to do this which delete option should I use to get the current bar 70 to move next to the current bar 68?
Sorry to ask but the terminology and my lack of experience (I'm a newbie to sequencers) is defeating me
Thanks

[spacefox]

It's the 'In' and 'Out' markers - the two red vertical lines you can drag around.

You can call the 'In' marker using the 'I' key, and the 'out' one using the 'O' key.