Usually when we route the PCB there are few chunks of tracks that are left after deleting segments of tracks... The problem arises when this segment is inside a pad so we cannot see it/ select it anymore. It is not very important because it does not changes anything on how the pCB will look like but the worries comes from the DRC check that monitors the dangling tracks. At the end of day I am left with 30/40 of those "errors" and I dont know which one is important
If you know the track segment is under a pad, simply use move the cursor to the pad, hold down the alt key and left-click till you "see" the segment. Holding the Alt key means you can select items that lie on top of each other in sequence. Sometimes takes a bit of effort depending on what you are trying to select/find, but it does work !
Another way of finding the 'lost' bits of track under a pad is to select the pad, then press 'n' (for next) until the bit of track is highlighted. The you can delete it.