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What is the difference between irme vs. ir. "Tengo que irme" is translated as "I have to go". I am confused as to why it would not be "Tengo que ir".

Irse (and the first-person singular version irme) is just an infinitive meaning "to go." The difference between "irme" and "tengo que irme" is the difference between "to go" and "I have to go."