Can I have the lease determined invalid to remove a tenant?

I am trying to evict a tenant, but know they're professional squatters, and can "work the system" for a while. Looking for another way out of this mess. I used a standard lease form for the lease with these tenants, but re-typed it to be able to add a "Hold Harmless" clause pertaining to the pool. Can I get the courts to determine the whole lease invalid with this clause? I'm in FL. Thanks.