Can A Admin User ( Not master Admin) delete the accounting records of a company in bulk, or RESET the QBO file completely using?

Hi there, Buck Tsai.

Yes, a Company admin can delete the accounting records of a company. However, not in bulk because this option is unavailable in QuickBooks. They can also reset the QBO file completely. The Company admin users have all access rights within QBO and to any other services your company is subscribed to. Except editing or removing your master admin's access.

If you don't want your user can access to delete the accounting records or give them limited access, you can add or change the company admin as Standard user. You can set different levels of access for this user. Please follow the steps below.

To add a user:

1. Click the Gear icon at the left panel. Then, Manage Users. If you can’t select this, you don’t have permission to manage other users. Contact an admin user for help.
2. Click the Add user.
3. Select the user type you want to create. 
4. Enter your new user’s name and email address.
5. Hit Save.

To change the Company admin to Standard user:

1. Click the Gear icon. Then, Manage Users.
2. Find the Company admin and select Edit in the Action column.
3. From the window that appears, choose the User type drop-down arrow menu.
4. Select the user type you want them to be.
5. When you’re done, hit Save. Ask the user to sign out and then sign in to see the changes.

For additional information, you can click this article: Add, delete, or change user access. This also provides details on how you can delete a user in the system.

Please check this article to see different user types and their levels of access in QuickBooks Online: User types and user permissions in QuickBooks Online.

Please know that you're always welcome to post if you have any other concerns. Wishing you and your business continued success.