Hiding QuickLaunch Items and Permissions on Site Navigation Items

Look for "PlaceHolderQuickLaunchBottom" content-place holder in your custom master page and remove the content in DIV tag . Add your static title and text in div below. 

<asp:ContentPlaceHolder id="PlaceHolderQuickLaunchBottom" runat="server">
                    <div class="ms-core-listMenu-verticalBox">
                        <SharePoint:ClusteredSPLinkButton
                            runat="server"
                            id="idNavLinkViewAll"
                            PermissionsString="ViewFormPages"
                            NavigateUrl="~site/_layouts/15/viewlsts.aspx"
                            Text="<%$Resources:wss,AllSiteContentMore%>"
                            accesskey="<%$Resources:wss,quiklnch_allcontent_AK%>"
                            CssClass="ms-core-listMenu-item ms-core-listMenu-heading" />
                    </div>
                </asp:ContentPlaceHolder>