deleting stuff from settings?

how do you delete things from settings? I know how to delete apps ( well the ones you are allowed to!) but I have a few VPN programs I downloaded but want rid of now ( they either didnt work or wanted money despite claiming to be "free" !) however despite removing the icons from the desktop they still appear in settings!
Ive tried a hard reset - still the same!
Is there some deeper level ordinary users can get into ? Like the registry on a windows PC?

 

Hi Missmouse - believe that we may have crossed paths before -

Not sure what exactly may be your issue(s), i.e. if these were DL to your stock iPad (assume that you are not jailbroken - but important to mention?), then a simple deletion should work; and a little confused about your description about 'stuff in settings' - please provide some additional information, e.g. what VPN programs or apps are you trying to delete and can you post an image of your settings page showing your concerns?