Lord Shri Ram is called ‘Sarvadaman’, that is, he can destroy everything at his will and no one can stop him. Lord Shri Ram is also called ‘Karunsagar’, which means he will deliver the salvation of all his devotees/devotees. The only thing we need to do is to become His devotee and completely surrender and depend on Him. Lord Shri Ram always saves his devotees and similarly destroys those who are against the religion. He did the same in this incarnation of Lord Shri Ram. Lord Shri Ram is the 7th incarnation of Lord Shri Vishnu. He killed many demons in his time. Below is the list of demons killed by Lord Rama:
Tatka
She was similar to Putna, who was killed by Shri Krishna in Dwapara Yuga / Mahabharata period. She was a Yaksha at her previous birth.
Khara and Dushan
Along with these two demons, Lord Sri Rama also killed fourteen thousand other asuras
Subahu
He was murdered on the instructions of Maharishi Vishwamitra.
Marich
He was first spared by Lord Shri Ram. But when he came in the form of a golden deer he was finally killed by Lord Sri Rama.
Bali
Although he was not a demon but he was an incarnation of Sri Indra Dev. He was killed by Lord Shri Ram because he had done many cruel deeds.
Makaraksha
He was the son of the demon Khara. He fought alongside Ravana and was eventually killed by Lord Sri Rama in the battle.
Kumbhakarna
He was killed in the battle of Lanka. He was the brother of Ravana and in his previous birth, he was born as Hiranyaksha. Also during the Dwapara Yuga / Mahabharata period, he was born as Dantavakra.
Ravana
He was killed by Lord Sri Rama in the battle in Lanka. In his previous birth, he had incarnated as Hiranyaksha. And in Dwapar Yuga/Mahabharat period he has taken birth as Shishupala.
Ahiravana
He was killed by Hanuman ji when he abducted Rama and Laxman and went to Patallok.
Kabandha
He was the one who had no neck or head and had only one eye. He was killed by both Lord Sri Rama and Sri Lakshmana.
Viradha
This demon tries to abduct Sri Sita Devi. He was blessed with an aashirvadam/boon that he would not be killed by any weapon. Seeing this Lord Shri Ram stood on this monster and Shri Lakshman buried this monster alive by digging a ditch.
Trishira (son of Ravana)
He was killed by Hanuman in the battle of Lanka.
Meghnath / Indrajit (Ravana’s son)
Killed by Sri Lakshmana in the Lanka war. He was reborn as Dushasana during the Mahabharata period.
Atikaya (son of Ravana)
He killed by Sri Lakshmana in the Lanka war.
Akshay Kumar (Son of Ravana)
He was killed through Sri Hanuman before the Lanka war. This happened when Sri Hanuman came down in search of Sri Sita Devi.
Narantaka (son of Ravana)
He was killed by Angada in the Lanka war.
Devantaka (Son of Ravana)
He was killed through Sri Hanuman.
Prahastha
He was killed by Nila in the Lanka war.
Other then this in many asur of Ravana were killed by Jambavant, Angad, Sugreev and Nal and vanar sena in Rama’s yuga.