To Place a Label Without a Leader

In the Drawing workflow, on the Annotation tab, in the Notes group, select the Place Label tool.
Select the Place Label Without Leader icon.
Select the Cell Name, Dimension Style, and Horizontal Attachment method.
(Optional) Turn on Place Label With Relative Association.
Enter a data point to select an element to which you want to snap the label.
Enter a data point to place the label.

Placing a Label Without a Leader