The fields in that screen are stored in an .xml file in the Layouts folder. So when you deleted the SambaPOS program folder, you ended up deleting the Layout file, in which case, SambaPOS will rebuild the file next time it is started, and by default, it will use all available fields from that Entity Type.
The Layout files will be in one of the following locations:
C:\Program Files (x86)\SambaPOS5\Layout\
C:\Users\USERNAME\Documents\SambaPOS5\Layout\
... the above is that same as:
[Documents]\SambaPOS5\Layout\
There will be Layout files for any of your configured Entity Screens - in the case of the Customer Search Entity Screen, the marked file below controls what is displayed, so in your case, you probably could have just deleted that file …
