Spark does not allow you to overwrite the files by default. There are two ways you can handle the situation.
You can either go to the location file:///tmp/spark-events delete the directory of the previous application or its logs.
Or you can just make Spark allow you to overwrite the log files:
val sc = new SparkContext(new SparkConf())
./bin/spark-submit <all your existing options> --spark.eventLog.overwrite=true