How to remove ?layout=item from urls

I have URLs that are generated as http://www.domainname.com/about?layout=item I would like to find out how to remove the ?layo开发者_如何学Cut=item and also ?layout=category

Any help would be much appreciated

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Following assumes that there is either layout=item or layout=category (not both at the same time)

RewriteCond %{QUERY_STRING} !^$
RewriteCond %{QUERY_STRING} ^(.*)(?<=&|^)layout=(item|category)&?(.*)$.
RewriteRule .* $1?%1%3