Disable/Hide Delete Item in Task list

Hi,

I have a Task list for the workflow. I am setting item level permission to the item to the "Approver","Requestor" and another custom group.

I had created a custom Role, which has the following permissions OpenItems,AddListItems,ViewListItems, EditListItems". The permission is not set for delete. However, the Approver is able to delete the task item.

The Approver is also part of another group which has contribute permission.

Is it possible to remove the delete permission to all the users explicitly for the Task list alone programmatically?

Thanks