The antonyms for the phrase "climbing up on" include descending, sliding down, lowering oneself, stepping down, and descending from. Climbing up on is used when referring to ascend or move upwards physically or metaphorically. On the other hand, descending means to move or go down from a higher place to a lower one. Sliding down refers to a way of moving down on a slippery surface. Lowering oneself implies going down or moving to a lower level. Stepping down involves carefully placing one foot down to move downwards. Lastly, descending from means moving away or detaching oneself from a previous position or status.