In QuickBooks Online:

If you have to edit a deposit you created, you would have to find it and and first delete it and start a new one. 

Me for example I accidently put it was coming out of a wrong bank account, and I had to go back and find it, luckily for me I found it in the banking screen, and it was wanting to be match to another deposit, I clicked on it from there and unselected items, and then deleted it. I then had to make another one with the corrections I needed. 

Its frustrating, and you would think there is a button for deposits being created in QBO, but I don't see it.