Answers for "maven only works after deleting target"

failed to delete surefirebooter.jar

Apart from IDE holding on to the jar, 
at times you will have some java process 
which could cause this as well. 
Lookup for any "java.exe" / "javaw.exe" process in task manager and kill it.

failed to delete surefirebooter.jar

Apart from IDE holding on to the jar, 
at times you will have some java process 
which could cause this as well. 
Lookup for any "java.exe" / "javaw.exe" process in task manager and kill it.