Tenant not paying rent and not vacating

We have a tenant with the rental contract since 1-12-2014.We need the property for own use and to renovate and sale it further. We have been requesting the tenant politely since over 2 years to vacate. The tenant comes up with excuses and begs and asks for more time. Apart from not vacating, tenant have not been paying rent properly since 3 years. The Tenant asked us to adjust the advance amount as rent, with the promise that he will vacate. However the Tenant have failed to vacate and not paying rent . The Advance amount adjustment completed over a year ago, since then the tenant is either not answering calls and not available at home. If coincidently find him in person he narrates grievances begging for more time with promise that he will pay rent regularly now on , which he failed to pay neither has vacated the premises. We have another tenant who turned like this tenant after looking at this tenant . Finally we have reached a stage both the tenants now not paying rent. Together finding ways to avoid us , not answering calls and threatening with false case /notices. Please advise how to proceed in this situation. The contract was made by a GPA holder , who is not able to chase them due to his busy work schedule . due to the fact that the tenants do not answer calls, when reach their home to talk about it hide inside or escape to avoid us.