Hello user62652,

I'm happy to share some information on this. Instant funding is an opt-in-only service, and once added to the account, it can't be disabled.  However, you don't have to cancel the Instant Deposit feature to avoid instant deposits by turning off the scheduling of them:

1. Within your account select the gear icon. 
2. Navigate to Accounts and Settings.
3. Select the Payments tab on the left.
4. Select Deposit Speed.
5. Set a schedule for instant deposit.
6. Click the All Days checkbox to toggle all days to Off.

Now, when a deposit becomes available, you should be prompted to mark it for Instant Deposit, or not.

1. Go to Settings ⚙ and select Account and Settings.
2. Select the Payments tab and go to the Deposit Speed section.
3. Select Change next to Scheduled instant deposits.
4. Uncheck the days to stop automatic instant deposits for those days. Then select  Save schedule.

If the deposit is already underway, canceling will not the instant deposit will not be possible. 

I'm linking a helpful article for you to look over as well: Get help with Instant Deposits.

Let me know if I can help with anything else. Take care!