Though I do not know how to remove that, I do know how to reduce/stop it with add-ons on a singleplayer/LAN server.
Download a playertype (Invincible Playertype, Boss Playertype etc) that has a bunch of health.
Enable it in custom.
Upon spawning, place a brick, click with wrench, click events, click the top left empty box next to the checked one.
It should bring up a list of things. select "OnActivate", and it should bring up another. Select "Player". Then click "ChangeDataBlock". Find the playertype, click it and click done on both tabs. Click the brick and you should have the playertype. Though some Custom Playertypes (Ones that change your model like the new Tracer Playertype) may reduce speed, weapon/tool space or max HP. (Tracer doesn't do any of these things, but changes jet to forward boost / blink.)