So no you can't cut off power and throw out the belongings of someone with a legal tenancy (I mean you *can*, but it's illegal). Your parents could issue him a notice of eviction (N12) for "personal use by landlord's family" (assuming you plan to move back in), since you are their son that is a legitimate reason to evict. They have to give 60 days' notice and pay one month's rent as compensation. Domestic issues between you and him are only relevant to potentially expedite the process if you are willing/able to file police reports etc and pursue the associated charges.

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If he refuses to leave as of the N12 then your parents would apply to the LTB for an eviction order and get him out that way.