Related article: Modifying Existing Routing
Altium Designer provides support for Loop Removal when routing using either the Multi-Trace or Differential Pair interactive routing tools.
As you route there will be many instances where you need to change some of the existing routing. Rather than attempting to change the existing routing using a drafting type approach of clicking and dragging track segments, you re-route. To do this, select the Interactive Differential Pair Routing or Interactive Multi-Routing command from the Place menu as applicable, click on the existing routing to start and then route the new path, coming back to meet the existing routing. This will create a loop with the old path and the new path, no need to worry though, as soon as you right-click or press Esc to terminate the route, the redundant segments are automatically removed, including any redundant vias.