Yes, you will have to use a lawsuit for removal of a person if he refuses to leave voluntarily, because he has established residency.
The three removal lawsuits are: ejectment (circuit court); unlawful detainer (county court); and eviction (county court).
If you never had an agreement for your son to pay rent, then you probably will want to use unlawful detainer, as he would not be called a tenant under that scenario.
If he ever paid rent or was supposed to pay rent, then he is a tenant and eviction is the proper lawsuit.
Ejectment is usually reserved for when the person is making a claim of title to the property.
See a local real estate attorney or landlord tenant lawyer if you need help.
If he doesn't pay rent the process may be called ejectment rather than eviction, but yes, unless you can persuade him to leave voluntarily.
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