"用手肘推开" can be translated into English as "push open with one's elbow" or "use one's elbow to push open".
For a more concise and natural-sounding expression in context, you might also say:
"Elbow it open" (informal and succinct, implying the use of the elbow to open or push something).
"Push the door/object open with your elbow" (for clarity in specific situations, like pushing a door).
Choose the phrase that best fits the context and level of formality you need.