When asking if you can omit celery, if you mean can you leave celery out of a recipe then the answer is yes. It is easy to replace celery as there are plenty of celery substitutes that will work within your recipe. When asking if you can omit celery and you mean, can you leave celery out of the fridge, this is a little tricker.  Celery is best stored in the fridge as the cool temperature will keep it nice and crisp for longer. Although, you can keep celery wrapped up in aluminum foil and leave at room temperature for up to a week and it will remain at top quality.