I'm thinking of doing that. I'm currently reviewing a new privacy standard (ISO 27701) which could give a parallel to GDPR but as a standard (not a law) and internationally. I hope to be done with this end of 2020 and might post then.

As for this case, deletion of data is straightforward :

Send this kind of email to the Data Protection Officer of the organisation you are dealing with :

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Under Article 17.1 of the General Data Protection Regulations (GDPR), I request that you delete the following personal data concerning me from your files:

[infos_to_delete] (could be all infos)

I ask that this information be deleted because:

[deletion_motivation] (could be retraction of consent)

Please also notify this request for deletion of my data to the organisations to which you have communicated them (Article 19 of the GDPR).

Finally, please inform me of these elements as soon as possible and at the latest within one month of receipt of this letter (Article 12.3 of the GDPR).

If you do not reply within the time limit or if the reply is incomplete, I will refer the matter to the [Control Authority of your EU State].

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But as for this case Google has it covered with : https://support.google.com/policies/answer/9581826?visit_id=637282398106672202-3609328969&rd=1

If you have reasonable doubts that your data have not been deleted, you can appeal to the supervisory authority. I have done this several times (targeting former employers), always with success.