He would step onto the podium to receive the medal, then step off the podium.
off' is being used as a preposition meaning :'moving away from, down from'
We can say, "Please step into my office."
These are prepositions used after the verb 'step' and before the noun (office/podium) - the noun telling us where the action of 'stepping' is directed towards or away from.
One can 'step down as Secretary of a committee', meaning, relinquish the office of Secretary.
A promotion at work can be termed 'a step up the career ladder'
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