Mistakes happen! When you hover over a comment, there’s a pencil icon that appears on the right side. When you click this, you’ll, be in “edit mode” where you can freely edit your comment (and remove files if uploaded too). Once you’re done, just click save.
Need to delete a comment? When you hover over a comment, you’ll see a trash can icon. When you click that, you’ll be shown a prompt to make sure you want to delete it. Confirm and you’re all set.
TIP: Anywhere you notice a "trash can icon", it's to delete and a "pencil icon" is for editing.