Hi everyone, my tenant hasn't paid rent for 4 years and isn't taking care of the house. I want to kick him out, but I'm looking for the cheapest way to do it.

Cheapest way? Consult your lawyer sir

Four years? Only one way bruh.

*Should Landlord Stop Rent-Owing Tenants from Moving Out? * by Onyekachi Umah, Esq., LL.M, ACIArb(UK)

In life you are either a tenant or a landlord and in some cases both. Many tenancy relationships go south with tenants failing to pay rents for years or landlords being rude, harassing and violating rights of tenants. The rate of landlords seeking to recover backlogs of unpaid rents (debts) from their tenants and former tenants is increasing geometrically across Nigeria. It is common to see cases of tenants who moved out of property “nicodemusly” (secretly) and ran away with unpaid rents. Often, bold rent-owing tenants or tenants that damaged any property get stopped by their landlords (using law enforcement agents, estate security and louts/thugs), when such tenants attempt to vacate property. This work examines whether a landlord should stop a tenant from vacating his property for any reason whatsoever in any part of Nigeria.

https://sabilaw.org/should-landlord-stop-rent-owing-tenants-from-moving-out/