First rub out the stain with compound, then polish the area with polish, then protect the finish with a good sealant over the entire car. I use this:
https://www.amazon.co.uk/Menzerna-Po...erna+powerlock
The rubbing and polishing can be done by hand on an area that small. You can do the sealant by hand as well, but a polisher like this makes it a lot easier:
https://www.amazon.co.uk/Hi-Spec-Act...GCQT4ZZ6S9W3SZ
Having the polisher you'll be able to do full car polishing when required. I do mine every spring.