The Replay button reloads the simulation and allows learners to complete it again. However, if you use the scenario question in the Assessment template you might want to limit the number of attempts and hide the Replay button.
To disable the Replay button, first you have to switch your simulation to the new player.
Create a new scenario question, click on Add Scenario, and the list of your existing simulations will show up. Under the simulation where you want to hide the Replay button, click on the three dots to extend the menu and choose Upgrade to new player.
When ready, you can go back to the original scenario question and start editing it.
In the scenario editor, go to Settings and disable the option to show the replay button.
Make sure to update/republish your course so that your changes are applied and become visible for learners.