How do I start fresh and remove all expenses from the account but keep everything else

I would recommend opening a new QBO account instead.

https://quickbooks.grsm.io/Canada

https://quickbooks.grsm.io/CFIB

If you still prefer to use your existing account, utilize a deleter tool

https://transactionpro.grsm.io/qbo

then utilize the trial version for a backup restore app

https://rewindio.grsm.io/quickbooks

Hello Emily. Welcome to the Community. QuickBooks gives you the flexibility you need in order to manage your income and expenses with peace of mind. It's vital you're able to get the info you need and I'll be happy to provide that so you can move forward. 

QuickBooks allows you to delete the data on your account only if your account is under 90 days of usage since the date you started your subscription. If your account is within 90 days, please follow the steps below to delete your data:
 

Important note: This process will delete all the data in the company file. Once you delete it, you can’t restore it. This process is only available to QuickBooks Online Plus, Essentials, and EasyStart. 

1. Log in to your QuickBooks Online Company.
2. Change the URL to include /purgecompany
   Example: Change https://sg.qbo.intuit.com/app/homepage to https://sg.qbo.intuit.com/app/purgecompany
3. The next screen will provide a summary of the items to delete. Type YES to delete the data, then select OK.

Here's an article with more info about deleting your data by purging the account. Otherwise, if you're looking to delete transactions from a specific date range, you'll have to manually delete the transactions using the helpful info in this article here. 

Feel free to ask other questions. I'm here to help you achieve your QuickBooks goals.