Nonviolence is an important duty for all humans in general of any caste:
"Nonviolence, truthfulness, honesty, desire for the happiness and welfare of all others and freedom from lust, anger and greed constitute duties for all members of society." (Bhagavata Purana, 11.17.21)
Killing anyone or anything is considered as sinful, in general.
However there are rare conditions where killing is ok:
"Lord Śrī Kṛṣṇa said: O Arjuna, you should not show mercy by releasing
this relative of a brāhmaṇa, for he has killed
innocent boys in their sleep.
A person who knows the principles of dharma does not kill an enemy
who is careless, intoxicated, insane, asleep, afraid or devoid of his
chariot. Nor does he kill a boy, a woman, a foolish creature or a
A cruel and wretched person who maintains his existence at the cost of
others’ lives deserves to be killed for his own well-being, otherwise
he will go down by his own actions." (Bhagavata Purana, 1.7.35-37)
ahiṁsā or nonviolence is an important principle in every form of Hinduism and mentioned over and over again in many scriptures.
"If one shows the symptoms of being a brāhmaṇa, kṣatriya, vaiśya or
śūdra, as described above, even if he has appeared in a different
class, he should be accepted according to those symptoms of
classification." - Bhagavata Purana, 7.11.35
A brahmana is someone with brahminical qualities (likewise the same for the other castes).
Someone who kills innocent people becomes an outcaste.
Don't you know that Ravana was from a brahmin family by birth but became known as an Asura? Ram was not from a brahmin family.
Overtime in this Kali Yuga the caste system became abused, distorted, and polluted.
In general, violence does not bring people closer towards perfection or unity with God, it pushes people away from God.