Left click the name in the Cell View until you get the cursor and just write over it. That's all there is to it. For interior cells, there's actually an "Interior Data" tab that comes up when you select to edit a cell, but exterior cells don't seem to give you that option.
To use the coc marker, call up the "console" with the tilda key ~ on the upper left corner of the keyboard then type coc the cell's name (as you see it in the cell view list), hit return and you should teleport right there. Be sure to check out the wiki!