Hello Karel,

Thank you for reporting this problem to us. It is actually a problem in the demo not in the component. Initially when no filter is applied the expression option is null. After deleting the cost filter the expression is an object. Later when someone calls set options we deep extend the objects and that is why the old cost filter is persisted. This is a pattern we follow through the entire suite. The problem can be resolved by saving a falsy value in the local storage if no filters are present. In other words the save logic can be modified as follows.

function saveState(e) {
            var expression = getFilter().getOptions().expression;
            localStorage["myFilterSettings"] = expression.filters ? JSON.stringify(expression) : "";
            // You can store and restore all options not just the expression.
        }

We will update our documentation sample as soon as possible to integrate this approach.

Regards,
Angel Petrov
Progress Telerik