You can manage your drafts by doing the following:
- Tap on your profile icon in the navigation bar to get to your Profile Screen
- Tap on the Drafts tab
- Tap on the 3 dots at the top right of the screen
- Tap "Manage Drafts"
- Select the draft(s) you want to delete
- Tap "Delete"
- Tap the back arrow
- You're done
Attached is a screen recording: