Article 17 of the UK GDPR includes the right to be forgotten. This means that a data subject can request that you delete their information without undue delay.
The right to be forgotten does not apply when:
processing is required for the performance of a public task (such as the maintaining of electoral registers)
it is necessary for archiving in the public interest
For example, an elector cannot ask the ERO to remove them from old or historical electoral registers because their inclusion on that register was a result of a legal obligation on the ERO.
However, an elector may request that information collected on grounds of consent (for example, where an elector gives consent to use of their email address) is deleted or removed at any time.
The RO is required to publish notices relating to an election. These notices may include personal information relating to candidates, subscribers and agents.
A person cannot use the right to be forgotten to require that their details are removed from a statutory notice.
However, they could exercise the right to have their details removed from a notice you have published on your council website after the election, if the deadline for an election petition had passed (when the notice serves no further purpose).
For this reason, once the petition deadline for an election has passed, you should either remove notices published on your website, or remove the personal data contained in these notices.
You should also consider whether it is appropriate to retain that data. For example, if you have existing records of email addresses or phone numbers collected through an application to register, at the time that you next use that information, you should take appropriate measures such as:
explaining the data subjects right to object to further processing
linking to your privacy notice
including the unsubscribe option, which allows the data subject to object to the use of their contact information for this purpose