Currently, the option to collapse the sub-accounts under the parent account is unavailable in both QuickBooks Desktop and QuickBooks Online. I appreciate you taking the time to share your suggestion in the Community and I'll make sure to take note and pass this along to our Product Developers for future product enhancements.
Right now, you can remove an account either by merging two accounts or hiding it by making it inactive. Let me show you how:
Click the Listsmenu, and then select Chart of Accounts.
Click the account you want to hide.
Click Accountat the bottom of the list, and then clickMake Account Inactive.