At one point I wanted to shorten the A-side of a clip in the time line, while making the B-side longer, while maintaining the sync of the two. To do this I used the Dual Roller Trim function, by clicking the mouse between the two clips until there were pink lines over them. A white symbol should also appear to show that the tool is in use. I dragged this too the left to achieve the look I wanted for the edit (reducing the A-side and extending the B-side).

Ready for the trim

Result : trimmed clips side by side

As you can see the left side clip is now significantly smaller, and the right is significantly longer than before. 

I wanted to get rid of this clip completely, without adding anything in it's place, but to delete it normally meant that everything afterwords would go out of sync (i.e. audio with visual). 

Clip to remove

Example of how if deleted the clips would go out of sync

To prevent this happening, I placed the playhead over the clip to be selected and used the shortcut 'T' to add automatic in and out points around the clip, as shown below.

Clip highlighted with marked in and out points by shortcut 'T'

I then used the Extract button to remove it from the timeline, leaving everything else in sync. 

Extract button

Result in timeline (nothing out of sync)