This article explains how you can withdraw your application.
If you applied for a service there two things that can happen: you are hired or you are not hired. It is always possible to withdraw your application as long as you have not been hired for the shift.
Note: If you still have applications open for shifts that start within 48 hours, you cannot withdraw them if you have been hired. For this you need to call the relevant company. You can therefore always withdraw your application as long as you have not yet been accepted.