if the checks you are getting are not clearning and thus the tenants are behind in rent, then you need to file an eviction action for failure to pay rent and evict them.  You can do this by hiring a lawyer or going to the clerk at the housing court and asking them to help you fill out an eviction notice and explain how you have to hire  a sherrif to serve it on the tenants.  You will give them a date to move out with 10 days or so.  If they dont move out you have to file a eviction action- the clerk can show you how to do that too or you can hire  a lawyer.  you just have to prove that you had a lease and they tenants are not paying rent and you served the eviction papers on them.  the court will order the tenants to leave.