Hi,
But that does not change the outcome, it is only a visual filter.
The post types, that had been selected under the General Options -> Sources panel will be used for search. If you want to limit the search to specific post types, then choose them there, the checkbox filter is not required of that.
If you still need them though, you can force hide them with this custom CSS:
.asp_checkboxes_filter_box {
display: none !important;
}