If you have forgeessentials installed on the server (It is a server side mod - so you don't need to worry about your players having to keep up to date with it)
/p group _GUESTS_ deny fe.teleport.back.*
This should disable the back command for returning to last death or last tp location.
The other constants for tp are:
Just replace fe.teleport.back.* with these and execute the command in game to disable that command for guest players.
Guests are anyone who joins the server who is not in a group (I think)
https://github.com/ForgeEssentials/ForgeEssentials/wiki/PermissionList.txt
fe.teleport.tp # (OP only: true)
fe.teleport.tpa # (default: true)
fe.teleport.tpa.here # (default: true) Allow teleporting other players to your own location (inversed TPA)
fe.teleport.tpa.loc # (OP only: true) Allow teleporting other players to any location
fe.teleport.tpa.sendrequest # (default: true) Allow sending teleport-to requests
fe.teleport.tpa.timeout # (default: 20) Amount of sec a user has to accept a TPA request
fe.teleport.tpahere.sendrequest # (default: true) Allow sending teleport-here requests
fe.teleport.tppos
Warp commands and Spawn commands can also be customized if needed
fe.perm.setspawn # (OP only: true)
fe.perm.user.spawn
fe.teleport.warp # (OP only: true)
fe.teleport.warp.admin # (OP only: true)
fe.teleport.warp.delete # (OP only: true) Allow deleting warps
fe.teleport.warp.max # (OP only: false) Maximal warp count
fe.teleport.warp.set
