A transitive verb (phrasal verb, verb phrase) always needs an object to receive the action. It's impossible to say "I get rid" - you need to tell us what you are getting rid of. "Every Spring I get rid of my old clothes."

The correct phrase is: Get rid of.... ...and MUST be followed by a direct object. Get rid of it. Get rid of that.

It is a transitive verb phrase because it needs to be followed by a direct object. Ex: Get rid of. (It is incomplete because it does not refer to an object.) Get rid of those dirty shoes! ("Get rid of" is referring to the shoes.) Get rid of that! (Even though the noun is not specified, this sentence is still okay because it has a direct object in it, "that".) So, it is a transitive verb phrase.