The option to Wrap up a Campaign will be available only when all runs are completed. If your Campaign has future scheduled runs, the wrap up option will not be available. But, you can Suspend the Campaign to modify the schedule as Paul suggested.
If the Campaign does not have any runs scheduled in the future but is still Running, I suggest you check the status of each of the initiated Campaign runs. If any of the runs are still running then the Campaign cannot be wrapped up. If there are any Campaign runs that are in a Failed state, these will need to be Skipped or Restarted.