Manage User Points
By going to Admin > Organization > Users, hovering over a user and clicking on the "Manage points", you are able to:
Remove the points for completed courses
Manually assign points to the user
When you click on "Manage points", you will find the list of the Points that were either gained for module completion, trophies or assigned manually to the user. In the search field you can serach for the module name to identify the module for which the points should be removed.
By clicking on "Assign points' you are able to add the number of points and add the reason for granting the points to the users.
Note: As per platform design, points achieved with trophies cannot be deleted. Alternatively, you may disable a trophy and that will remove both the trophy and the points for all users in the platform.
Check this article if you want to learn how to disable trophies.