Dear friend,
From a legal perspective, the provision for Casual Leave allowed to the workers of the factory so far becomes a customary concession or privilege under item no. 8 of the Schedule-IV of the IDA, 1947. Therefore, as an employer, you cannot dispense with it without issuing a notice u/s 9-A or under a bilateral settlement with the workers.
If such employees working from home are employed in an establishment other than a factory, you have to see whether there is a provision for Casual Leave in the employment-specific labor law applicable there.
That aside, how do you think that Casual Leave becomes redundant in respect of employees working from home? Are they not required to be logged on compulsorily during the entire normal working hours?