Create iRule to remove everything after a string found in the URI

this is just another example.

 configuration

[root@ve11b:Active:In Sync] config  tmsh list ltm rule qux
ltm rule qux {
    when HTTP_REQUEST {
  set uri [HTTP::uri]
  if { $uri contains "format=XYZ" } {
    HTTP::uri [string map {"&format=XYZ" "" "format=XYZ&" "" "format=XYZ" ""} $uri]
  }
  log local0. "Before: $uri After: [HTTP::uri]"
}
}

 /var/log/ltm

[root@ve11b:Active:In Sync] config  tail -f /var/log/ltm
Jun 10 22:03:00 ve11b info tmm[10343]: Rule /Common/qux : Before: /data/ After: /data/
Jun 10 22:03:09 ve11b info tmm[10343]: Rule /Common/qux : Before: /data/12345=rank&format=XYZ After: /data/12345=rank
Jun 10 22:03:17 ve11b info tmm1[10343]: Rule /Common/qux : Before: /data/format=XYZ&12345=rank After: /data/12345=rank
Jun 10 22:03:27 ve11b info tmm[10343]: Rule /Common/qux : Before: /data/test=abc&format=XYZ&12345=rank After: /data/test=abc&12345=rank