It's the nightmare of all Landlords, the Bad Tenant.
No one wants them, and you're probably kicking yourself that you may have been able avoid them, 'if only' you had done X,Y, Z. Well you can't go back in time, so the next step is to deal with them here and now.
But what do you do?
First of all it depends on what is happening? Not paying rent, being rude to the neighbors, destroying your property (pulling out water heaters, tearing up the floor, setting fires etc)