LTM VE 10.2.3: HTTP::uri

If I may add, the HTTP::uri write command, on most platforms, does not actually rewrite the client request URI in session state - it only changes the value on the outgoing payload. Your iRule is definitely changing the URI on its way to the server, you just won't see that change in [HTTP::uri].

Also not completely sure what you were doing with the SELECTED_POOL variable, so here's a minor rewrite:

when CLIENT_ACCEPTED {
     set default_pool to pool assigned to the virtual server
    set default_pool [LB::server pool]
}
when HTTP_REQUEST { 
    set DEBUG 1 
    switch -glob [string tolower [HTTP::uri]] { 
        "/cm/*" { 
            pool "LPAGE_ALERTAS"
        } 
        "/delivery/wifi*" { 
            set newuri [findstr [string tolower [HTTP::uri]] "/delivery" 9] 
            HTTP::uri $newuri 
            if { $DEBUG } { log local1. "LPAGE_APPLICATION URI MODIF:: $newuri - [HTTP::uri]" }
            pool $default_pool
        } 
        "/delivery*" { 
            pool $default_pool 
        } 
        default { 
            if { $DEBUG } { log local1. "LPAGE_APPLICATION :: blocked request for [HTTP::uri] by [IP::client_addr]" }
            HTTP::respond 403
        }
    } 
}