My personal experience as of Dec 2019 with requesting (SE wide) removal of my (other) account via the [contact form](https://meta.stackexchange.com/contact), selecting the `Other` topic, was very positive. It was completely handled within minutes:

[![enter image description here][1]][2][![enter image description here][3]][4][![enter image description here][5]][6]

Note: each message had the following text in the footer:
"*You’re receiving this email because you recently used Stack Overflow’s Data Access Request service.*" linking to the [Submit a Data Access Request form](https://stackoverflow.com/legal/gdpr/request). For future GDPR requests I would try to use that form instead of the contact form.


  [1]: https://i.sstatic.net/diWwJm.png
  [2]: https://i.sstatic.net/diWwJ.png
  [3]: https://i.sstatic.net/y8aODm.png
  [4]: https://i.sstatic.net/y8aOD.png
  [5]: https://i.sstatic.net/rgcG0m.png
  [6]: https://i.sstatic.net/rgcG0.png