frighten off
phr. v..phr. v.. to make a person or animal go away by making them feel scared.
phr. v.. to cause a person or animal to leave or avoid a situation by inducing fear or apprehension; often used when a potential threat or unwanted presence is removed.
The loud dog barked to frighten off the burglars.
The company raised its prices so much that it managed to frighten off most of its loyal customers.
Conservationists worry that increased tourist activity in the valley will frighten off the rare birds that nest there during the spring.
this is a transitive phrasal verb that can take either a physical or abstract object.
compare with 'scare off', which is more common in casual speech; 'frighten off' is slightly more formal but still very natural in everyday British and American English.
The noise frightened off them.The noise frightened them off.when the object is a pronoun like 'them', it must go between the verb and the particle.