Yes you can - as long as you have not yet submitted your form. 
The delete option appears on the 'Page 5 - Consent' section of the form as below. 


If you have already submitted your claim, add a Note to your claim to tell the team that you have uploaded the wrong evidence. You can also add more documents as evidence after you have submitted your claim. 

What if I have more documents to add?

Simply select 'Back' from this screen and uploaded via the 'Supporting evidence' page once again.