* Disaccustom: This is the most direct opposite, meaning to make someone unfamiliar with something again.
* Unaccustom: Similar to disaccustom, this word indicates a lack of familiarity.
* Unfamiliarize: This word implies making someone unfamiliar with something they were once accustomed to.
* Dishabituate: This word refers to the process of breaking a habit or becoming less accustomed to something.
* Alienate: This word can be used when someone is made to feel strange or unwelcome in a situation they were once accustomed to.
The best antonym will depend on the specific situation and the nuance you want to convey.