You can teleport players to entities and armor stands are entities so they're good markers for this purpose. Place an armor stand and name it with a name tag (such as 'pos1'). Then you can teleport the player to the armor stand with the following command.

    /tp @p @e[name=pos1]

If you want to move the armor stand without having to replace and rename it, you can teleport the armor stand to your current position.

    /tp @e[name=pos1] @p

If you don't want the armor stand to be visible you can grant the armor stand an invisibility effect with particles disabled for a really long time.

    /effect @e[name=pos1] invisibility 99999999 0 true

If you wish to remove the armor stands you can kill them easily with commands

    /kill @e[name=pos1]