small black bar in top of clips in fcpx timeline - unable to move clips around

Hi, I need help with the following. 
Some of the video clips on my timeline have a black bar in top and im not able to cut parts of the clips and move them around. Please see the screenshot attached. What is this black bar and how can I remove it?  Please see in the screenshot the clip on the right (which doesnt have this bar on top) vs the clip on the left (which has the bar on top) Thanks

That’s the shelf of a secondary storyline. There might be a transition at the other end of the clip that created it to link the clips together. You can move the storyline by dragging the shelf. You can also drag a clip out of the storyline. I might suggest looking at basic tutorials on FCP like the izzyvideo free tutorials.

Highlight then to Clip Menu for Break Apart Clip Items (Command+Shift+G). Or highlight then Command+Option+down arrow (WARNING) drops it to primary storyline and displaces anything beneath it.