I created a workflow that creates a ‘request deletion’ button using the Add Button workflow action. I would like to remove the ‘request deletion’ button after it has been triggered. However, I am not able to remove the button within the workflow. My ‘request deletion’ button is not available in the Button dropdown for the Remove Button workflow action in the next State.

If I remember correctly, the add button action should only be for that state. If you are sending the workflow to another state, you shouldn't have to remove it...it shouldn't exist there.