Good morning, c-larson-bridgef.
Thanks for turning to the Community for support. I'm happy to share info regarding your question about the undeposited funds account in QuickBooks Online.
To hide the undeposited funds account from the account options when making a deposit you may consider making it inactive. Here's how:
1. Click the Gear icon in the top right corner and choose Chart of Accounts.
2. Locate the Undeposited Funds account and click the black Action drop-down arrow to the right.
3. Select Make inactive.
The following article provides additional info about making an account inactive on your chart of accounts in QuickBooks Online. Lastly, this link provides details on using journal entries in QBO.
Please feel free to comment below if you have any other questions. I'll be here to help.