====/igg/cancellesson====
Cancel an existing lesson

parameters:
|auth	|the authorisation code you received from Intogolf BV (mandatory)|
|crsnr	|the id of the course (mandatory)|
|relnr	|the id of the golfer that is currently logged in (mandatory)|
|relkey	|the hash key that was provided upon login (mandatory if relnr>0)|
|lesnr	|id of the lesson to be canceled (mandatory)|


example: https://backend.ikgagolfen.nl/igg/cancellesson?auth=<your authorisation code>&crsnr=1&lesnr=167075&relnr=707025&relkey=a8d2aaaef4131d033d60cdfd0bfe9804

result (if succesful):
<code>{
  "cancellesson": [
    {
      "errorcode": 0,
      "errormsg": ""
    }
  ]
}</code>

Possible errorcodes are:
|1	|lesson not found|
|2	|lessontype not found|
|3	|relation was not found in golfcourse database|
|4	|relation was not found in lesson|
|5	|lesson not canceled|

if a wrong authorisation code is provided, the backend will return “no authorisation”