can the lessor terminate the contract due to unpaid rentals

the lessee of our building did not pay the monthly rentals for two months and issued postdated checks without sufficient funds yet with lapse time, he slowly paid it partially.. lately, he showed undesirable attitude since he wont entertain us when we tried to collect for the rentals and is unable to pay for two months now. we like to terminate the contract, since we ask for 3 months advance, can we terminate the contract and ask them to vacate the building without obligation to pay the balance of the advance rentals? since they are the ones who violated the contract, can we demand for immediate termination even if the contract made was just put into writing but not sealed by attorneys?....what are the right thing or the best thing to do regarding this matter that is law abiding...please i need legal advice..i want to know my rights and proper actions to do..thanks and god bless...

did you deposit these unfunded checks? were they dishonored by the bank?

what does your contract say about pre-termination of the lease?