When searching in the activities launcher of Ubuntu you may want to see only some preferred results. By default, when you search in activities you get app results, file results, etc. For example, if you don’t want to see results from files then you can customize search preferences by following the steps given below.
Go to Settings.
Choose Search from the left panel. From there you can customize your search preferences by toggling. If you don’t want to see file results then you can toggle it off. You can even disable the whole search option by using the toggle button given at the right top.