To change any Developer Configurations, you must be logged in as an install or site administrator.
You can use custom settings instead of webcustom.config entires.
FWAppSettings.GetValue(“Key”)
for siteSettings/web.config entries as well as webcustom.config/custom site settings.SiteSetting.Instance.CustomSettings(“Key”)
for custom site settings.To delete a custom setting, click the X icon at the end of the listing.
Note: Remember values in the Admin UI site settings override the web.config values(if any).