4 days after lip fillers, top lip is too big, can I partially dissolve instead of dissolving all of it?

It's too soon to tell what your final results will be. You have swelling, which can be asymmetrical, and last 1-2 weeks after lip injections. If you're unhappy with your final results, you can have it reversed with hyaluronidase and try a different technique next time. See an expert. Best, Dr. Emer

It is potentially possible to inject small amounts of hyaluronidase to partially dissolve filler.  It can be tricky.  I would definitely wait 2 whole weeks prior to considering it however, because the lips tend to hold on to swelling for a while.  And if you are thinking that you didn't have much swelling last time you got injected, remember that every time is different in terms of swelling.  Make sure you avoid salty foods to minimize swelling over the next few days while you let things settle.  

Swelling can be typical. Icing and cold compresses may give improvement. I would wait a full 2 weeks before judging the results. If it is after the two week wait, you can have the filler reversed with hyaluronidase.
I hope this helps!