You can choose between two options to delete tracks:
In any tracks list, swipe across a row from right to left – you should then see a button to delete the item. This is a standard gesture that works across many other apps from Apple (Mail, Notes,…) and other 3rd parties.
Alternatively, tap the title on a track’s detail screen. You can edit the track’s information or tap the delete button at the bottom.
In the waypoints list, use the swipe gesture (see above).
On a waypoint’s detail screen, tap the trash icon in the upper right corner.
Go to Settings > Tags and use the swipe gesture (see above) to delete tags.