I am not using Site Pages and Pages Library in my Site. Can I delete them from Site Contents? Will that effect my Site negatively.
The short answer is that deleting them will cause issues for your site.
The reason for this is that these page libraries are added by default when a Site is created so that SharePoint knows where to look for specific items, in this case pages.
So what's the difference between "Site Pages" and "Pages"? I hear you asking. At the base level, one is used for "Wiki pages" and the other for Branding pages (as found here).
More details can be found on this question: The diffence between Pages and Site Pages
it is not recommended to do so, but it is possible , if you can't see "Delete this document library" option you can use power-shell as below to allow Deletion
$web = Get-SPWeb http://sp/sites/xyz $list = $web.Lists["Site Pages"] $list.AllowDeletion = $True $list.Update() or you can delete it directly $web = Get-SPWeb http://sp/sites/xyz $list = $web.Lists["Site Pages"] $list.Delete()
deleted library and list will be moved to recycle bin and you can restore it later