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• In XMLUI, use Advanced Policy Manager. Log in as an administrator, in the Administrative menu, click Authorizations (under Access Control.) Then in the main pane, under the search box, there's a link to the tool (Advanced authorizations tool: Click here to go to the item wildcard policy admin tool).
• You can write a curation task (DSpace 1.7 and newer, see DSpace 1.8: Curation System, Curation Task Cookbook)
• You can write custom SQL query on the "resourcepolicy" table.

How do I remove the search box from the front page in XMLUI?

This will remove the search box from the homepage body and keep the search box in the menu:

<xsl:template name="disable_front-page-search" match="dri:div[@id='aspect.discovery.SiteViewer.div.front-page-search']">
</xsl:template>