Most employers will allow you to delete your application before the application deadline, and also after the recruitment process has been completed. In the intervening time, i.e. while the applications are being assessed, you will not be able to delete your application, but you will be able to withdraw it. If you withdraw your application, it will still be visible to the recruiter, but it will be clear that you no longer wish to be considered.
Therefore, in any sent application you will see the option to either withdraw the application...
... or delete it:
If you have requested the expanded applicant list for this position (relevant for some public-sector organisations), the list will be removed from Sent applications when you withdraw your application.
Note: You cannot re-apply for the same position once you have withdrawn your application.
If you simply want to make some changes to your application, do not withdraw it – what you need to do is update it. See the chapter “Update the application”.