When you say "pull back extension line to the arrow" I assume that you want your extension line to disappear.
If that is what you want to do, you should select the dimension and on the properties palette turn off the extension line.
The advantage is that the defpoint will still be at it's original location.
You can turn of just one or both extension lines using the properties palette.
If you want this for all dimensions I would create a dimension style and with the extension lines suppressed.
