jQuery.inArray returns the first index that matches the item you searched for or -1 if it is not found:
if($.inArray(valueToMatch, theArray) > -1) alert("it's in there");
You shouldn’t need an array.remove. Use splice:
theArray.splice(startRemovingAtThisIndex, numberOfItemsToRemove);
Or, you can perform a “remove” using the jQuery.grep util:
var valueToRemove="someval";
theArray = $.grep(theArray, function(val) { return val != valueToRemove; });