The following command deletes the rule named contentrule.

Situation before delete:

Before deleting the content rule, the showrule command can be run to display a list of currently installed rules.

<?xml version="1.0" encoding="ISO-8859-1"?>
<Response stat="200" code="ok">
<Success><Data><MatchContentRule>
<Name>contentrule</Name>
<Pattern>pattern</Pattern>
<MatchType>Regex</MatchType>
<AddHost>N</AddHost>
<Negate>N</Negate>
<CaseIndependent>N</CaseIndependent>
<IncludeQuery>N</IncludeQuery>
<Header></Header>
<MustFail>N</MustFail>
</MatchContentRule>
</Data>
</Success>
</Response>
curl -k "https://bal:1fourall@20.200.25.100/access/delrule?name=contentrule"

Situation after delete: 

<?xml version="1.0" encoding="ISO-8859-1"?>
<Response stat="200" code="ok">
<Success><Data></Data>
</Success>
</Response>