How do you translate "off" in Spanish. Por ejemplo,"Get off the sofa", o "Get off the Baby". To get off an object.

It would be inferred.

¡Bájate de la sofá! - Get down off the sofa!
¡Déjala/lo! - Leave her/him alone! (If the person were very close to or touching baby, it's tough for me to imagine a situation where someone would actually be on a baby)
¡Deja de pisar mi pie! - Stop stepping on my foot! (Get off my foot!)

'Note: These are all in the tu form, because it is doubtful that you would use 'usted'.

Think of "get off" as one verb. The "off" particle will NOT translate and the verb will be imperative.

¡Bájate del sofá! - Get down off the sofa!

¡Déjala/lo! - Leave her/him alone! (If the person were very close to or touching baby, it's tough for me to imagine a situation where someone would actually be on a baby)

¡Deja de pisarme el pie! - Stop stepping on my foot! (Get off my foot!)

Sorry, Nathaniel, nothing personal, but "sofá" is masculine (yes, it ends in -a, I know, it is not logical, but we took this word from French, and for them it was masculine already. The word is ultimately Persian). Also, for parts of the body, we rarely use possessives (mi, tu, su,...), specially if we can use direct/indirect pronouns instead.

Sorry, Nathaniel, nothing personal, but "sofá" is masculine (yes, it ends in -a, I know, it is not logical, but we took this word from French, and for them it was masculine already. The word is ultimately Persian). Also, for parts of the body, we rarely use possessives (mi, tu, su,...), specially if we can use direct/indirect pronouns instead.

I fail to see how it would be anything personal if you want to ensure that correct grammar is used.

This is a learning site, and I am still learning. Thank you.