Problem with report filter

I want to filter a report for a specific item of the data source with no ability for the user to change this filter. If I use report filter, they can change it. I would like to be able to specify that this item will not be changed. I have found a solution in setting the filter in the visual element filter, but after that, I was not able to supress the report filter (after saving the filter is still there !). I had to create again the report !