The adjective unwarranted means unjustified, lacking a good reason, unnecessary or nonsense.
Synonyms are needless, inessential, disposable, or gratuitous.
The word origins from un meaning “not” + past participle of warrant. Its first known use was in 1577.
Her opinion was completely unwarranted.
Allergies are seriously unwarranted but should never be neglected.
Their request to investigate the barista was unwarranted so it wasn’t approved.