Stop Salary of employees for breach of Companies Policies

I am a Director of a company and I had to terminate a few employees, as they were creating nuisance. So we terminated their contract on the grounds of the process being shut down, while one filed a resignation himself. They all stopped coming to the office after they got their salary of the previous month, i.e on the 15. Now they are expecting me to pay the salary of this particular month of July. The worst part is that, they have deleted majority of the content they worked on in the company and we have a clause in the confidentiality agreement signed by both me and my employee which states that they will have to surrender all the content upon termination of the contract. Secondly, there is another clause, which states that if they are found to be in breach of the agreement, they shall be liable for the sum, they have received in the last three months. I have a proof, that they have deleted the content and moved it out of the company. So, is it legal for me to stop their salaries for this month, wherein they were serving the notice period? If I don't pay the salary to them on the grounds of breach of agreement, do I have to face any consequences for this? Is there a way for me, to stop their salaries?