Licensee terminated the lease and not paying dues what can I do

Licencee has given only 2 weeks notice instead of one month for termination of agreement and not paid last month licencee fee / electric bill / etc he has handed over the keys / possession but i am left with no choice but to deduct unpaid monthly fees and other expenses, and asked him to issue a letter that this is full and final but he has refused to sign and demanding that i pay back his security deposit after deducting for only 2 weeks - what is my recourse ? hold the deposit till he signs off or pay as per my calculation and let him sue for the balance ? how easy it is to claim legally