As an alliance leader, how can I teleport back to my territory?

You can use either a Fortress teleport (moves you to near the alliance fortress if you have one) or an advanced teleport that lets you select where to move to. For this last one just finds the alliance territory and tap on the map where you want to land and select teleport.

You can buy both of those items in the alliance store.

If you need to locate the alliance area on the map, Look for the pins of the alliance members of if you have alliance buildings they will show up.