You can delete a comment that you have made on someone's project by logging into your Crowdfunder account and clicking on My Pledges
Next you need to click on the project title of the project page that you have made a comment on.
Then navigating to the 'Comments' tab, underneath your comment, you will see a 'Remove comment' button....
If you made the comment through 'Guest check out', then you can create an account through your pledge receipt email, or go to the forgotten password page and enter the email address you used to pledge and follow the instructions in the email.
If you are a project owner looking to hide a supporters comment click here for instructions.