Please follow the mentioned settings steps to save only the edited version of the screenshot:
realme UI 3.0 & above versions: Settings > System & updates / System settings / Additional settings > Screenshot > turn on Delete original image after editing
realme UI 2.0: Settings > Convenience tools > Screenshot > turn on Delete original image after editing
realme UI 1.0: Settings > Additional settings > Screenshot > turn on Delete original image after editing
realme UI R & Go Edition: Not supported
Process: Take the screenshot and click on the left-hand side of the screenshot directly. You will get the option to edit the same, do the editing, and choose the right icon (✓) to save the edited version.
Note: This option only applies to the screenshot