An ACH Deposit (transferring money from another bank into Qube) that you've initiated from within the Qube App can be canceled within the first 15 minutes of submitting the order. After 15 minutes, the deposit cannot be canceled. You'll need to wait until the deposit completes and then transfer it back to where it came from.
For an ACH Deposit into Qube that you've initiated from your other bank's website, you'll need to go to that bank's website to see if a scheduled/pending external transfer can be canceled, as they are in control of sending it, not Qube.
Click here for more information on depositing money into your Qube account.